Patent Description:
This application claims the benefit of priority of <CIT>.

The present invention, in some embodiments thereof, relates to a crystal structure and, more particularly, to a spin-selective conduction structure.

Spintronics refers to the utilization of electron spin to carry out logic and electronic operations. Spintronics allows for harnessing the spin degree of freedom to realize new functionalities while the energy needed for manipulation of the spin is relatively low compared to classical electronics. Chiral-induced spin-selective (CISS) electronic conduction was demonstrated in bio-inspired chiral thin organic films, such as dsDNA, peptides, and proteins.

Organic-molecule-based magnets have been recently studied [<NPL>; <NPL>; <NPL>; <NPL>; <NPL>; <NPL>; <NPL>; <NPL>; <NPL>; <NPL>; <NPL>; <NPL>; and <NPL>]. Such compounds are known to exhibit magnetic properties, useful for spintronic elements and quantum devices.

According to an aspect of some embodiments of the present invention there is provided a spin-selective conduction structure. The spin-selective conduction structure comprises a crystal having a monolayer of metal atoms between two layers of chiral organic molecules, wherein each metal atom is coupled to two chiral organic molecules, one at each layer, and wherein a chirality of organic molecules in one of the two layers is the same as a chirality of organic molecules in a another one of the two layers.

According to some embodiments of the invention the spin-selective conduction structure wherein a chirality of all of the organic molecules in each layer is the same.

According to some embodiments of the invention the crystal is arranged as a stack comprises a plurality of monolayers of the metal atoms, each monolayer being between two layers of the chiral organic molecules.

According to some embodiments of the invention a thickness of the stack, perpendicular to the monolayer, is at least <NUM>, more preferably at least <NUM>, more preferably at least <NUM>, more preferably at least <NUM>, more preferably at least <NUM>.

According to some embodiments of the invention the metal atoms are selected to reduce quantum de-coherence of spin states.

According to some embodiments of the invention the spin-selective conduction structure is characterized by spin-polarization of at least <NUM>%, more preferably at least <NUM>%, more preferably at least <NUM>%.

According to some embodiments of the invention the chiral organic molecules comprise chiral aromatic molecules.

According to some embodiments of the invention the chiral organic molecules self-assemble to form the layers.

According to some embodiments of the invention the crystal is noncentrosymmetric and is characterized by a space group P2<NUM>.

According to some embodiments of the invention the crystal is noncentrosymmetric and is characterized by a space group P1.

According to some embodiments of the invention the chiral organic molecules comprise chiral amino acid molecules.

According to some embodiments of the invention amino and carboxylic acid moieties of the amino acid molecules are ligands forming the coupling.

According to some embodiments of the invention the chiral amino acid molecules comprise aromatic amino acid molecule.

According to some embodiments of the invention the chiral amino acid molecules comprise D-phenylalanine.

According to some embodiments of the invention the chiral amino acid molecules comprise L-phenylalanine.

According to some embodiments of the invention the chiral amino acid molecules comprise D-pentafluorophenylalanine.

According to some embodiments of the invention the chiral amino acid molecules comprise L-pentafluorophenylalanine.

According to some embodiments of the invention the chiral amino acid molecules comprise D-tryptophan.

According to some embodiments of the invention the chiral amino acid molecules comprise L-tryptophan.

According to some embodiments of the invention the chiral amino acid molecules comprise D-tyrosine.

According to some embodiments of the invention the chiral amino acid molecules comprise L-tyrosine.

According to some embodiments of the invention the chiral organic molecules comprise chiral peptides, less than <NUM> amino acids in length, more preferably less than <NUM> amino acids in length, more preferably less than <NUM> amino acids in length, more preferably less than <NUM> amino acids in length, e.g., <NUM> amino acids in length. According to some of these embodiments, each amino acid residue in the peptide features the same chirality (L or D).

According to some embodiments of the invention the chiral organic molecules comprise chiral metabolites.

According to some embodiments of the invention the metal atoms comprise copper atoms.

According to some embodiments of the invention the metal atoms comprise cobalt atoms.

According to some embodiments of the invention the metal atoms comprise nickel atoms.

According to some embodiments of the invention the metal atoms comprise platinum atoms.

According to an aspect of some embodiments of the present invention there is provided a method of generating current. The method comprises applying energy to the spin-selective conduction structure as delineated above and optionally and preferably as further detailed below, so as to generate flow of charge carriers through the structure.

According to an aspect of some embodiments of the present invention there is provided a method of storing information. The method comprises applying energy to the spin-selective conduction structure as delineated above and optionally and preferably as further detailed below, so as to trap electrons at a preselected spin in the structure.

According to some embodiments of the invention the energy is applied by directing electromagnetic radiation to the structure. According to some embodiments of the invention the energy is applied applying voltage to the structure.

According to some embodiments of the invention the spin-selective conduction structure comprises a semiconductor substrate, wherein one of the layers of chiral organic molecules is deposited on the semiconductor substrate.

According to an aspect of some embodiments of the present invention there is provided a method of generating current. The method provides the spin-selective conduction structure as delineated above and optionally and preferably as further detailed below, and generates condition for charge carriers in the semiconductor substrate to travel through the layers of chiral organic molecules.

According to some embodiments of the invention the method exposes the chiral organic molecules to electromagnetic radiation, so as to generate the condition for the charge carriers in the semiconductor substrate to travel through the layers of chiral organic molecules.

According to some embodiments of the invention the method applies voltage to the semiconductor substrate, so as to generate the condition for the charge carriers in the semiconductor substrate to travel through the layers of chiral organic molecules.

According to an aspect of some embodiments of the present invention there is provided a spintronic circuit. The spintronic circuit comprises the spin-selective conduction structure as delineated above, and optionally and preferably as exemplified herein.

According to an aspect of some embodiments of the present invention there is provided a spintronic circuit. The spintronic circuit comprises an active layer on a semiconductor substrate, wherein the active layer comprises a metal-organic chiral crystal characterized by an electrical resistance that reduces in response to a flow of an electrical current therethrough.

According to some embodiments of the invention the spintronic circuit is incorporated in a device selected from the group consisting of a magnetic field sensor, a memristor, a magnetic memory device, a spintronic transistor, a spin filter device, a spin valve, a spin switch, a spin-polarized light emitting diode (LED), a quantum computer, and a data reading head for reading data from magnetic storage medium.

According to some embodiments of the invention the spintronic circuit comprises a source electrode, a drain electrode, a gate electrode, and a magnetic field generator.

According to some embodiments of the invention the spintronic circuit comprises a controller configure to vary a gate voltage applied to the gate electrode, and a magnetic field applied by the magnetic field generator, so as to provide at least three distinct source-drain current states.

Some embodiments of the invention are herein described, by way of example only, with reference to the accompanying drawings and images.

It was found that due to the quantum-mechanical nature of the CISS effect, quantum de-coherence limits the length- and time-scale of the phenomenon to several tens of nanometers. The present disclosure provides a metal-organic chiral crystal that achieves spin-selective conduction using metal atoms and chiral organic molecules. The crystal conducts current in a spin-selective manner, based on the CISS effect, owing to the chiral environment in conjunction with the conducting metal atoms. The inventors experimentally demonstrated spin-selective conduction over a range that is larger than <NUM>. In some embodiments of the present invention the crystal is characterized by an electrical resistance that decreases in response to a flow of an electrical current therethrough. This is unlike conventional oxide-based devices in which the current applied increases the resistance, since the current fills charge trap states.

<FIG> is a schematic illustration of a spin-selective conduction structure <NUM>, according to some embodiments of the present invention. The structure comprises a crystal <NUM> having a monolayer <NUM> of metal atoms <NUM> between two layers <NUM>, <NUM> of chiral organic molecules <NUM>. Each metal atom is optionally and preferably coupled to two chiral organic molecules <NUM>, one at each of layers <NUM> and <NUM>. The chirality of organic molecule <NUM> in one of the two layers <NUM> and <NUM> is the same as a chirality of organic molecule <NUM> in the other one of the two layers <NUM> and <NUM>.

According to some embodiments of the invention the chiral organic molecules <NUM> are chiral aromatic molecules.

According to some of any of the embodiments described herein, each of the aromatic molecules comprises an aromatic amino acid.

According to some embodiments of the invention, the chiral organic molecules, e.g., chiral aromatic molecules, self-assemble to form said layers.

By "aromatic molecule" it is meant a molecule (a compound) that comprises at least one aromatic moiety or group.

As used herein, the phrase "aromatic group" or "aromatic moiety" describes a monocyclic or polycyclic moiety having a completely conjugated pi-electron system. The aromatic group can be an all-carbon moiety or can include one or more heteroatoms such as, for example, nitrogen, sulfur or oxygen. The aromatic group can be substituted or unsubstituted, whereby when substituted, the substituent can be, for example, one or more of alkyl, trihaloalkyl, alkenyl, alkynyl, cycloalkyl, aryl, heteroaryl, heteroalicyclic, halo, nitro, azo, hydroxy, alkoxy, thiohydroxy, thioalkoxy, cyano and amine.

Exemplary aromatic groups include, for example, phenyl, biphenyl, naphthalenyl, phenanthrenyl, anthracenyl, [<NUM>,<NUM>]phenanthrolinyl, indoles, thiophenes, thiazoles and, [<NUM>,<NUM>']bipyridinyl, each being optionally substituted. Thus, representative examples of aromatic groups that can serve as the side chain within the aromatic amino acid described herein include, without limitation, substituted or unsubstituted naphthalenyl, substituted or unsubstituted phenanthrenyl, substituted or unsubstituted anthracenyl, substituted or unsubstituted [<NUM>,<NUM>]phenanthrolinyl, substituted or unsubstituted [<NUM>,<NUM>']bipyridinyl, substituted or unsubstituted biphenyl and substituted or unsubstituted phenyl. The aromatic group can alternatively be substituted or unsubstituted heteroaryl such as, for example, indole, thiophene, imidazole, oxazole, thiazole, pyrazole, pyridine, pyrimidine, quinoline, isoquinoline, quinazoline, quinoxaline, and purine.

In some of any of the embodiments described herein, the aromatic molecule comprises at least one aromatic moiety that is an all-carbon aromatic moiety, e.g., an aryl.

In some of any of the embodiments described herein, the aromatic molecule is or comprises an aromatic amino acid.

In some of any of the embodiments described herein, the aromatic molecule is an aromatic amino acid.

By "aromatic amino acid" it is meant an amino acid, or an amino acid residue in a peptide comprising same, that has an aromatic moiety or group, as defined herein, is its side chain. In exemplary embodiments, an aromatic amino acid has, for example, a substituted or unsubstituted naphthalenyl or a substituted or unsubstituted phenyl, in its side chain. The substituted phenyl may be, for example, pentafluoro phenyl, iodophenyl, biphenyl and nitrophenyl.

According to some embodiments of the invention the chiral organic molecules comprise chiral amino acid molecules. According to some embodiments of the invention the chiral amino acid molecules comprise aromatic amino acid molecule. According to some embodiments of the invention the chiral amino acid molecules comprise D-phenylalanine. According to some embodiments of the invention the chiral amino acid molecules comprise L-phenylalanine. According to some embodiments of the invention the chiral amino acid molecules comprise D-pentafluorophenylalanine. According to some embodiments of the invention the chiral amino acid molecules comprise L-pentafluorophenylalanine. According to some embodiments of the invention the chiral amino acid molecules comprise D-tryptophan. According to some embodiments of the invention the chiral amino acid molecules comprise L-tryptophan. According to some embodiments of the invention the chiral amino acid molecules comprise D-tyrosine. According to some embodiments of the invention the chiral amino acid molecules comprise L-tyrosine.

According to some embodiments of the invention the chiral organic molecules comprise chiral peptides, less than <NUM> amino acids in length, more preferably less than <NUM> amino acids in length, more preferably less than <NUM> amino acids in length, more preferably less than <NUM> amino acids in length, e.g., <NUM> amino acids in length. According to some of these embodiments, each amino acid residue in the peptide features the same chirality (L or D). According to some embodiments of the invention the chiral organic molecules comprise chiral metabolites.

According to some embodiments of the invention the amino and carboxylic acid moieties of the amino acid molecules are ligands forming the coupling between the molecules and the metal atoms.

According to some embodiments of the invention the metal atoms <NUM> are selected to reduce quantum de-coherence of spin states. According to some embodiments of the invention the metal atoms <NUM> comprise copper atoms. According to some embodiments of the invention the metal atoms <NUM> comprise cobalt atoms. According to some embodiments of the invention the metal atoms <NUM> comprise nickel atoms. According to some embodiments of the invention the metal atoms <NUM> comprise platinum atoms.

According to some embodiments of the invention the crystal is characterized by spin-polarization of at least <NUM>%, more preferably at least <NUM>%, more preferably at least <NUM>%.

<FIG> illustrates a configuration in which crystal <NUM> has single monolayer <NUM> of metal atoms <NUM> and two layers <NUM> and <NUM> of organic molecules <NUM>. However, this need not necessarily be the case, since, for some applications, it may be desired to have crystal <NUM> arranged as a stack comprising a plurality of monolayers <NUM> of the metal atoms <NUM>, each monolayer <NUM> being between two layers <NUM>, <NUM> of the chiral organic molecules <NUM>. Representative examples of such stacks are illustrated in the Examples section that follows. According to some embodiments of the invention a thickness of the stack, perpendicular to the monolayer, is at least <NUM>, more preferably at least <NUM>, more preferably at least <NUM>, more preferably at least <NUM>, more preferably at least <NUM>.

According to some embodiments of the invention spin-selective conduction structure <NUM> comprises a semiconductor substrate <NUM>. One of the layers of the chiral organic molecules <NUM> is deposited on semiconductor substrate <NUM>. Substrate <NUM> can comprise any semiconductor material, such as, but not limited to, an elemental semiconductor of Group IV and various combinations of two or more elements from any of Groups III, IV, V and VI of the periodic table of the elements.

As used herein, the term "group" is given its usual definition as understood by one of ordinary skill in the art. For instance, group III elements include B, Al, Ga, In and Tl; Group IV elements include C, Si, Ge, Sn and Pb; Group V elements include N, P, As, Sb and Bi; and Group VI elements include O, S, Se, Te and Po.

For example, when substrate <NUM> comprises silicon, substrate <NUM> can comprises can be a silicon oxide or silicon nitride. Other example include, without limitation, silicon oxynitride, aluminum oxide, aluminum oxynitride, hafnium oxynitride, hafnium aluminum oxide, hafnium silicon oxide, hafnium silicon oxynitride, zirconium silicate, hafnium dioxide and zirconium dioxide and the like.

Other types of substrates that are contemplated for use as substrate <NUM> include, without limitation, binary III-V semiconductor alloys, such as, but not limited to, InAs, InSb, InP GaSb, GaAs and AlSb, ternary III-V semiconductor alloys such as, but not limited to, InGaAs, InAsSb, InAsP, AlInAs, AlAsSb, GaAsP and InSbP, and quaternary semiconductor alloys such as, but not limited to, GaInAsSb.

Spin-selective conduction structure <NUM> can be incorporated in a spintronic circuit. According to some embodiments of the invention the spintronic circuit is incorporated in a magnetic field sensor. According to some embodiments of the invention the spintronic circuit is incorporated in a magnetic memory device. According to some embodiments of the invention the spintronic circuit is incorporated in a spintronic transistor. According to some embodiments of the invention the spintronic circuit is incorporated in a spin filter device. According to some embodiments of the invention the spintronic circuit is incorporated in a spin valve. According to some embodiments of the invention the spintronic circuit is incorporated in a spin switch. According to some embodiments of the invention the spintronic circuit is incorporated in a spin-polarized light emitting diode. According to some embodiments of the invention the spintronic circuit is incorporated in a quantum computer. According to some embodiments of the invention the spintronic circuit is incorporated in a data reading head for reading data from magnetic storage medium.

Spin-selective conduction structure <NUM> can be used for generating current. For example, energy can be applied to structure <NUM>, to generate flow of charge carriers through the structure.

Spin-selective conduction structure <NUM> can be used for storing information. For example, energy can be applied to structure <NUM>, to trap electrons at a preselected spin in the structure.

The energy can be applied, for example, by directing electromagnetic radiation to the structure, or by applying voltage to the structure.

In some embodiments of the present invention conditions are generated for charge carriers in semiconductor substrate <NUM> to travel through the layers <NUM>, <NUM>, <NUM> of crystal <NUM>.

This can be done in more than one way. In some embodiments of the present invention the structure <NUM> is exposed to electromagnetic radiation, for example, to light. This can be done by means of an electromagnetic radiation source <NUM>, such as, but not limited to, a light source, configured for generating electromagnetic radiation <NUM>. In various exemplary embodiments of the invention radiation <NUM> is monochromatic radiation wherein the wavelength of radiation <NUM> is selected to generate the condition for charge carriers in semiconductor substrate <NUM> to travel through the layers <NUM>, <NUM>, <NUM>.

In some embodiments of the present invention voltage is applied to the semiconductor substrate <NUM> by means of a source electrode <NUM> and a drain electrode <NUM>, connected to a voltage source <NUM>, as to generate the condition for the charge carriers in the semiconductor substrate to travel through the layers of chiral organic molecules <NUM>, <NUM>, <NUM>.

A representative example of a spintronic circuit <NUM>, according to some embodiments of the present invention is illustrated in <FIG>. In these embodiments, the spintronic circuit <NUM> can be used as a memristor.

The term "memristor" is short for "memory resistor. " A memristor is a nonlinear component combines a persistent memory with electrical resistance. In other words, a memristor has a non-linear resistance that can act as a universal memory that enables logic operations. The memristor of the present embodiments acts differently from known oxide-based inorganic memristors. In particular, the memristor of the present embodiments comprises a crystal, such as, but not limited to, crystal <NUM>, that is characterized by an electrical resistance that decreases in response to a flow of an electrical current therethrough. This is unlike conventional -based inorganic memristors in which the current applied increases the resistance, since the current fills charge trap states.

Spintronic circuit <NUM> comprises an active crystal, such as, but not limited to, crystal <NUM> on substrate <NUM>, source electrode <NUM>, and drain electrode <NUM>. In some embodiments of the present invention circuit <NUM> also comprises a gate electrode <NUM> for applying a gate voltage to substrate <NUM>, and optionally and preferably also a magnetic field generator <NUM> for applying a magnetic field to crystal <NUM>. Preferably, but not necessarily, the magnetic field lines are generally parallel to the source-drain direction defined between source electrode <NUM> and drain electrode <NUM>. The Inventors found that such a configuration allows memristor <NUM> to exhibit multilevel memory states. In particular, it was found that different directions of the magnetic fields, and different gate voltages induce different memory states in memristor <NUM>. Thus, a controller <NUM> is optionally and preferably configure to vary the gate voltage applied to gate electrode <NUM>, and the magnetic field applied by magnetic field generator <NUM>, so as to provide a plurality (e.g., three or more) distinct memory states. As demonstrated in the Examples section that follows, the Inventors successfully fabricated a memristor that exhibits six memory states using two levels for the gate voltage and three different magnetic field characteristics.

Utilization of thiolated double stranded DNA (dsDNA) as a spin-selective component in a spin filter device <NUM> is illustrated <FIG>, and described in <CIT>. The thiolated dsDNA is bound to a gold surface <NUM>, and forms a self-assembled mono-layer <NUM> of chiral molecules. Unpolarised electrons <NUM> ejected from the gold surface produced by linearly polarised light <NUM> incident from the monolayer side are transmitted and can be analyzed. Most of the electrons <NUM> transmitted through the monolayer <NUM> are spin polarised. Spin orientation depends on the enantiomer used in the monolayer. The dephasing limits CISS conduction. For example, in some embodiments of the present invention the dephasing limits the CISS conduction several tens of nm.

This Example describes a particular bioinspired class of a metal-organic chiral crystals comprising Cu(II) atoms arranged in two-dimensional (2D) layers of D- or L-enantiomers of phenylalanine or pentafluorophenylalanine. This Example shows experimental observation of a thermally activated ferromagnetic component, occurring at temperatures higher than about <NUM>. This makes the materials potentially weakly multi-ferroic, that is, possessing a combination of ferroelectric and ferromagnetic properties. Such behavior has, to date, been identified at room temperature only in inorganic materials. The onset of ferromagnetism is accompanied by a significant increase in long-range (above <NUM>), spin-selective electron conduction. Without wishing to be bound to any particular theory, the Inventors, based on electron paramagnetic resonance (EPR) studies and density functional theory (DFT) calculations, attribute the unexpected magnetic behavior to an indirect exchange interaction between the Cu(II) ions through the chiral lattice. It is expected that the discovered combination of chirality and magnetic properties, exists also in other chiral metal-organic crystals, and can also be used in spin-based devices.

In an exemplified embodiment of the present invention, the spin-selective conduction structure comprises bio-inspired self-assembled organometallic crystals formed by D- or L-phenylalanine and with copper (D/L-Phe-Cu, respectively) and/or D- or L-pentafluorophenylalanine with copper (D/L-F<NUM>Phe-Cu, respectively). In experiments performed by Inventors of the present invention, these materials self-assembled in water into a structure in which two chiral amino acid molecules coordinate a copper (II) ion. This formed a crystalline structure made up of a continuous layer of copper atoms sandwiched between the chiral amino acid environment.

It was experimentally found that the Phe-Cu and F<NUM>Phe-Cu crystallized into noncentrosymmetric crystal structures, where D- and L-Phe-Cu are mirror images of each other and D- and L-F<NUM>Phe-Cu are non-symmetric. These crystals are plate-like, with a diameter ranging from <NUM> to <NUM> in diameter, proving relatively simple to use in nano-, micro- and macro-sized applications.

It was experimentally found that the formed crystals conduct current in a spin-selective manner, based on the CISS effect, owing to the chiral amino acid environment in conjunction with the conducting metallic centers. The inventors demonstrated spin-selective conduction for long ranges (more than <NUM>) with good spin-polarization values of about <NUM>%.

All materials were purchased from Sigma-Aldrich (Israel) unless noted otherwise. Pentafluorophenylalanine was purchased from Chem Impex (USA). All amino acid-copper crystals were obtained using the following general method: <NUM> equiv of the CuCl2 (<NUM>% CuCl2 purity, <NUM>) aqueous solution was slowly added to <NUM> equiv of an amino acid (<NUM>) alkaline solution containing <NUM> equiv of NaOH (<NUM>) under heating at <NUM>. Spontaneously, plate-like blue crystals started growing at the liquid-air interface. The crystals were filtered off, washed with deionized water, and dried under vacuum.

Blue plate-like crystals suitable for diffraction were coated with Paratone oil (Hampton Research) and mounted on a MiTeGen loops and flash frozen in liquid nitrogen. All X-ray diffraction measurements were done at <NUM>. Diffraction measurements for L-Phe-Cu were done at ESRF synchrotron, station ID23-<NUM>. Data were collected and processed using MXCube and the automated XDS pipeline. Data for D-Phe-Cu were measured in-house on a Bruker ApexKappaII. Data were collected and processed using the Bruker Apex2 software suite. D/L-F<NUM>Phe-Cu crystals were measured in-house on a Rigaku XtaLabPro full Kappa diffractometer. Data were collected and processed with CrysAlisPro. All structures were solved by direct methods using SHELXT-<NUM> or SHELXT <NUM>/<NUM>. The structures were refined by full-matrix least-squares against F<NUM> with SHELXL <NUM>/<NUM>. The crystallographic data are given in Table <NUM>, below. The structure was illustrated using Mercury <NUM> (Cambridge Crystallographic Data Centre, Cambridge, UK).

CD spectra were obtained at <NUM> using an Applied Photophysics Chirascan CD spectrometer, equipped with a temperature-controlled cell, at <NUM> resolution, as an average of three measurements. Spectra were subtracted and smoothed using the Pro-Data software (Applied Photophysics).

A common way to identify ferroelectricity in a material is by measuring the change of the permittivity as a function of an applied electric field (ε-E) or the equivalent capacitance versus applied voltage (C-V) curves. The ε-E or C-V measurements are typically done by applying simultaneously on the sample a variable DC voltage and a constant small AC voltage of relatively high frequency (<NUM> or above). The AC voltage is used to measure the capacitance, which is then plotted as a function of the DC bias field or voltage. In this example, the C-V curve of L-Phe-Cu crystals was measured using an impedance analyzer (Alpha; Novocontrol) at <NUM> AC frequency.

Magnetic measurements of L-Phe-Cu crystal were performed using MPMS3 SQUID magnetometer (LOT-Quantum Design Inc. ) by applying a vibrating sample mode. The sample was placed in a standard brass holder. The temperature dependence of the magnetic moment was taken at FCH mode: the sample was cooled to <NUM> under a <NUM> Oe magnetic field. Samples were measured while heating from <NUM> to <NUM>. Magnetic field dependencies were taken at different temperatures in the intervals while the magnetic field H was decreased and increased in the range -<NUM> kOe ≤ H ≤ + <NUM> kOe (at some cases the interval was lengthened: ± <NUM> kOe). The lamellar shape of the crystals before their grinding completely corresponds to the orientation of the layers in the crystal structures (<FIG>). This allowed us to measure the difference in magnetic properties with the applied magnetic field oriented perpendicular and parallel to the plane crystal layers (plane ab).

CW-EPR spectra were recorded on a Bruker Elexsys E580 spectrometer operating at X-band (<NUM>) and Q-band (<NUM>) frequencies and outfitted with an EN4118X-MD4 resonator for X-band measurements and with an EN-<NUM>-D2 for Q-band measurements. The temperature was controlled by an Oxford Instruments CF935 continuous flow cryostat using liquid He. Experimental conditions were <NUM> points, with a microwave power of <NUM> mW, <NUM> mT modulation amplitude, and <NUM> modulation frequency for X-band measurements. The sweep range was <NUM> mT. For Q-band measurements, the experimental conditions were <NUM> points, with microwave power of <NUM> mW, <NUM> mT modulation amplitude and <NUM> modulation frequency. The sweep range was <NUM> mT.

Gold electrodes, <NUM> apart from each other, were fabricated in a van der Pauw geometry on a thermal oxide (SiO<NUM>-<NUM>) p-type silicon wafer.

With reference to <FIG> (top left inset), in the first measurement, a <NUM>µA current was applied between electrodes <NUM> and <NUM> (I<NUM>), and the voltage difference was measured between electrodes <NUM> and <NUM> (V<NUM>), producing the resistance RA (V<NUM>/I<NUM>). In the second measurement, the same current was passed between electrodes <NUM> and <NUM> (I<NUM>), and the voltage was measured between electrodes <NUM> and <NUM> (V<NUM>), producing the resistance RB (V<NUM>/I<NUM>). The sample resistance (RS) was calculated the using the formula: <MAT>.

Substrate surfaces were prepared by sputtering a <NUM> layer of nickel, followed by an <NUM> layer of gold on top of a silicon wafer with a <NUM> thermal silicon oxide layer, with an <NUM> titanium layer for adhesion. The use of the Ni/Au surfaces for the mAFM measurements allowed magnetic-field-induced spin polarization of the electrons injected from the surface to the crystal. All surfaces were cleaned by boiling first in acetone and then in ethanol for <NUM>, followed by a UV-ozone cleaning for <NUM> and a final incubation in warm ethanol for <NUM>. The solution of the crystal was drop-casted on the surface and kept in vacuo for evaporation. <FIG> present the shape of the crystals and their structure.

Magnetic-field-dependent current versus voltage (I-V) characteristics of the crystals were obtained using a multimode magnetic scanning probe microscopy system built with Beetle Ambient AFM and an electromagnet equipped with a R9 electronics controller (RHK Technology). Voltage spectroscopy for I-V measurements were performed by applying voltage ramps with a Pt tip (DPE-XSC11, µmasch with spring constant <NUM>-<NUM> N m-<NUM>) in contact with the sample at an applied force of <NUM> nN. At least <NUM> I-V curves were scanned for both magnetic field orientation (field UP and DOWN). The crystals were deposited on a gold-coated nickel (Ni <NUM>, Au <NUM>) silicon substrate. The magnetization direction of the nickel layer (up or down) was controlled by an external magnetic field, oriented perpendicular to the Ni plane.

Geometric structure optimizations and electronic structure calculations were performed using the Vienna ab Initio Simulation Package plane wave basis code. Crystal geometric optimizations were performed for the ferromagnetic and antiferromagnetic states separately using the Perdew-Burke-Ernzerhof generalized-gradient approximation exchange- correlation functional, augmented by Tkatchenko-Scheffler van der Waals (TS-vdW) dispersion corrections. Ionic cores were addressed by the projector augmented wave method. The Brillouin zones of all examined crystals were sampled using a Monkhorst-Pack k-point grid of <NUM>×<NUM>×<NUM>, with a plane wave energy cutoff of <NUM> eV, following convergence tests with respect to both parameters. For electronic structure calculations, the screened-hybrid functional of Heyd, Scuseria, and Ernzerhof was used. These methods were found to produce reliable results in molecular crystalline materials. Magnetization was calculated by subtracting the up and down spin densities of the crystal and illustrated using the VESTA software.

D- and L-enantiomers of phenylalanine and pentafluorophenylalanine were separately crystallized with copper ions (D/L-Phe-Cu and D/L-F<NUM>Phe-Cu, respectively) and characterized by X-ray crystallography and circular dichroism (CD) spectroscopy (see the Methods section for details). The asymmetric units of both types of crystals comprise an amino acid dimer coordinating a copper atom (<FIG>, see also <FIG>, and Table <NUM> for crystallographic data), where the amino and carboxylic acid moieties of the amino acids act as ligands. The unit cells (see <FIG>, <FIG>) assemble to form a layered crystal structure containing an ordered layer of copper atoms, sandwiched between the chiral environment consisting of the amino acids (see <FIG>, <FIG>). The Phe-Cu and F<NUM>Phe-Cu crystals arrange into noncentrosymmetric space groups, P2<NUM> and P<NUM>, respectively. The shape of the crystals is shown in <FIG>. The L and D unit cells and crystal structures are mirror images of each other (<FIG>). CD spectroscopy was used to confirm the chirality of the crystals, showing opposite CD absorption spectra of the two enantiomers (<FIG>). The main absorption band of Phe-Cu is located at <NUM>-<NUM>, showing a positive (negative) Cotton effect for the D-Phe-Cu (L-Phe-Cu) crystal. F<NUM>Phe-Cu has a main absorption band at <NUM>-<NUM>, with a positive (negative) Cotton effect for the D-F<NUM>Phe-Cu (L-F<NUM>Phe-Cu) enantiomer. UV-vis characterization, along with determination of the stoichiometric content of the Cu ions, is provided in <FIG>.

The ferroelectric response of the crystals was examined. The equivalent capacitance versus applied voltage (C-V) curves of L-Phe-Cu crystals using an impedance analyzer at a frequency of <NUM>. At very low temperature, <NUM>, the samples behave as a perfect capacitor, showing no maximum in the capacitance with the applied DC voltage. At <NUM> (<FIG>), the C-V curve exhibits several peaks in the capacitance, similar to the curve of multidomain ferroelectric materials. After a few cycles, the capacitance drops and the C-V curve stabilizes, becoming smoother with only two peaks near zero voltage, which implies that the coercive field of this material is relatively small. Above about <NUM>, the samples behave as conductors, precluding the measurement of capacitance.

Magnetic properties of these materials were measured using a superconducting quantum interference device (SQUID). The inventors used ultrapure materials for the crystallization and repeated the measurements for different batches, ruling out bulk contamination. Furthermore, measurements were performed on both single crystals and microcrystalline powders to rule out surface contamination. For the single crystals, <FIG> and <FIG> present the magnetic moment as a function of applied magnetic field parallel or perpendicular to the ab crystal plane, respectively. A strong predominantly paramagnetic response that decreases with temperature is observed. Surprisingly, the low-field region of the magnetic response (<FIG> and <FIG>) features a ferromagnetic response at temperatures above about <NUM>, revealed by an increasingly broadened hysteresis curve that persists even at <NUM> (as reflected in the coercive field shown in <FIG> and <FIG>). Corresponding results of powder measurements are shown in <FIG> and <FIG>. The magnetic results point toward a thermally activated exchange interaction, with an activation temperature in the range of from about <NUM> to about <NUM> (about <NUM>-<NUM> meV). The magnetic behavior is similar to that observed in 2D magnets, except for the unusual thermally activated ferromagnetism.

The behavior of the magnetization as a function of temperature, measured at a <NUM> Oe magnetic field, is further analyzed using the Curie-Weiss equation, χ-<NUM>=(T-Θ)/X, where χ is the magnetic susceptibility, T is the absolute temperature, and C and Θ are, respectively, the Curie-Weiss constant and temperatures (<FIG> and <FIG>). Fitting the parameters of this equation against the measured χ-<NUM> as a function of temperature (FIGs. 9A-D3) for the high-temperature regime (<NUM>-<NUM>), yields a positive Θ, indicating ferromagnetic interactions. When the fit is performed at a lower temperature range, Θ is reduced, and at sufficiently low temperature, Θ becomes negative, indicating antiferromagnetic properties.

To further support the magnetic data, EPR spectra were measured for the L-Phe-Cu crystalline powder at both the Q- and X-bands (<FIG> and <FIG>, respectively). At <NUM>, the EPR signal is strong, indicating mainly localized spin. With a temperature increase, the signal intensity decreases gradually, indicating an enhanced exchange interaction due to increased thermal motion and hence some delocalization of the unpaired electrons. The EPR results are therefore consistent with a temperature-activated exchange interaction between the Cu(II) ion and the lattice.

The magnetic measurements were augmented by temperature-dependent conduction measurements, performed using four gold contacts in a Van der Pauw geometry (<FIG> and <FIG>). This configuration allows the measurement of conduction in the ab plane of the crystals. <FIG> shows the dependence of the surface resistance, RS, on the temperature. A substantial increase in resistance was observed at low temperature, starting at about <NUM>. This correlates well with the observed loss of ferromagnetism and is similar to the behavior observed at a metal-insulator transition.

To explore spin-dependent conduction, room-temperature spin-dependent electron conduction studies were performed using a magnetic conductive probe atomic force microscope (mCP-AFM), based on a setup shown in <FIG>. The crystals were deposited on a gold-coated nickel (Ni <NUM>, Au <NUM>) substrate. The substrate magnetization direction (up or down) was controlled by an external magnetic field, oriented perpendicular to the Ni plane (for details, see the Methods section). The AFM was fitted with a nonmagnetic Pt tip. Prior to the conduction studies, the morphology of the samples was analyzed using AFM topography images (<FIG>), and it was established that the conduction measurements are performed along the short (about <NUM>) c-axis of the crystals. Measurements were taken at different sites of each crystal and for several crystals of each type, and are shown in <FIG>.

<FIG> show the obtained current-voltage (I-V) curves for D- and L-Phe-Cu crystals (<FIG>) and D- and L-F<NUM>Phe-Cu crystals (<FIG>). Each curve is an average over <NUM> to <NUM> individual measurements (see <FIG> and <FIG>). The I-V measurements indicate that the <NUM> thick crystals behave as a large-gap semiconductor. Spin-dependent conduction is observed, even though the electrons are transported through a much longer medium than in former studies on chiral systems. For D-Phe-Cu (L-Phe-Cu), the current is higher when electrons are injected from the down-magnetized (up-magnetized) substrate. The opposite is true for the F<NUM>Phe-Cu crystal. Quantitatively, at +<NUM> V, the degree of spin polarization, defined as (IU - ID)/(IU + ID), where IU and ID are the currents measured with the Ni magnetized up and down, respectively, is about <NUM>% (about <NUM>%) for the D-Phe-Cu (L-Phe-Cu) enantiomer. Correspondingly, the spin polarization measured for the F<NUM>Phe-Cu crystal was found to be about <NUM>% (about <NUM>%) for the D(L) enantiomer. Although ferroelectric behavior at room temperature could not be ascertained directly, the asymmetry observed in the I-V curves may be explained by a net polarization in the crystals.

Based on the CISS effect alone, the current magnitude for the L-enantiomer with the up-magnetized substrate should be the same as that for the D-enantiomer with the down-magnetized substrate. <FIG> and <FIG> show that this is not the case. Instead, for Phe-Cu (F<NUM>Phe-Cu), the current measured with the L-enantiomer is generally higher (lower) than that for the D-enantiomer. This can be rationalized by the observed room-temperature ferromagnetism. Whereas the preferred spin injection depends on the handedness (L or D), the preferred spin transport also depends on the magnetization direction of the molecular ferromagnet, independent of chirality. Therefore, a large current is observed only if both effects support the same spin preference. Given that all measured crystals were magnetized with a magnetic field pointing up (see detailed discussion in the Methods section), this is indeed the case for L-Phe-Cu (<FIG>): when the injected spin is up (i.e., spin aligned antiparallel to the electron velocity), both conditions for spin transfer are favorable and conduction is high; when the opposite spin is injected, it is not preferred by chirality or magnetization, and the current is low. For the D-enantiomer, chirality does not prefer the injection of spin-up electrons. However, the magnetism allows their conduction through the crystals. Hence, only one condition for conduction is fulfilled. For injection of spin-down, the chirality condition is favorable for the spin but the magnetic condition is not. Thus, in the case of the D-enantiomer, there are never two optimal conditions for spin transport and therefore the current is intermediate.

To gain insight into the unconventional electronic and magnetic properties of the crystals, DFT calculations were performed. Computational details are given in the Methods section. Computational results for the L-enantiomer are shown in <FIG>. Results for the fluorinated crystals are very similar and are shown in <FIG>.

Both ferromagnetic and an antiferromagnetic state were stabilized in the DFT calculations, with the energy of the antiferromagnetic state being lower by about <NUM> meV per unit cell. The density of states for the ferromagnetic and antiferromagnetic phases of L-Phe-Cu is given in <FIG>, and the associated spin density distribution is given in <FIG>. The data show that the spin density is mainly centered on the copper atom and adjacent ligand moieties. Orbital-resolved densities of states, are shown in <FIG>. The entire Cu + ligand entity can then be thought of as one spin-polarized unit, which couples in-plane, ferromagnetically or antiferromagnetically, to nearby Cu + ligand units, resembling 2D magnetic phenomena. Hence, the Cu<NUM>+ ions are coupled indirectly, even at the geometry corresponding to the low-temperature structure, with the molecular moieties surrounding each Cu<NUM>+ ion playing a role in facilitating the magnetism.

Interpreting the energy difference between the ferromagnetic and an antiferromagnetic states as the thermodynamic energy needed to flip the spin density at and around one Cu<NUM>+ ion in the unit cell, these results suggest that no ferromagnetic response is expected below about <NUM>, which, given the approximations inherent in the calculations, is in good qualitative agreement with experiment. At higher temperatures, one can expect some filling of the ferromagnetic state and therefore coexistence of ferromagnetic and antiferromagnetic states, explaining the onset of ferromagnetic hysteresis and its above-discussed impact on transport. The spin density suggests that for a given spin-polarized electron these states facilitate transport from one Cu<NUM>+ ion to its adjacent neighbor for the ferromagnetic state but not for the antiferromagnetic state, where the same spin polarization occurs only on the second-nearest neighboring Cu<NUM>+ ion. This explains why the conductivity drops for temperatures low enough such that the antiferromagnetic state dominates (see <FIG>).

It is noted that dynamic phenomena may also explain temperature-activated ferromagnetism. Magnetic order may form owing to the interaction of the spin on the copper ion with lattice dynamics in the crystals, or by a magnetic field created locally by acoustic chiral phonons, which is manifested as an enhanced long-range exchange interaction. A possible role of chirality in obtaining temperature-activated ferromagnetism is that when the Cu<NUM>+ ion vibrates against the chiral lattice, it causes charge polarization. Because of the chirality, the charge polarization is accompanied by spin polarization, which in turn induces spin polarization on the next Cu ion. Such a dynamic effect would be consistent with the EPR results presented above.

This Example showed that bioinspired chiral metal-organic crystals support room-temperature, long-range, chirality-induced spin-selective electron conduction. These crystals are found to be weakly ferromagnetic and ferroelectric. The observed ferromagnetism is thermally activated, so that the crystals are antiferromagnetic at low temperatures and become ferromagnetic above about <NUM>. Without wishing to be bound to any particular theory, this unexpected behavior can be explained in terms of indirect interaction between the unpaired electrons on the Cu ions, mediated via the chiral lattice, which results in a low-lying thermally populated ferromagnetic state.

This Example describes the use of chiral metal-organic crystals with non-conventional magnetic properties, for the fabrication of an organic chiral spin nonlinear spin memory-resistor (memristor), based on the CISS effect. The device described in this Example consists of an irregular memristor loop, which depends on both the charges and spin trapping. This Example demonstrates that a simple device can exhibit multilevel controlled states, generated by the magnetization of the source. In this Example, changing the source magnetization slows a six-level readout for two terminal organic devices.

The main application found for organic materials in electronic applications is the organic light-emitting diodes (OLED). For memory applications, organic materials suffer from having relatively low conductivity and large variability. In spintronics, although organic materials having a notable relatively long spin lifetime, the low conduction and the need to interface organic materials with inorganic ferromagnetic electrodes make the use of organic materials a challenge.

This Example presents chiral metal-organic crystals (MOCs), as organic materials that have relatively good conduction and in addition, interesting magnetic properties, and demonstrates the use of these crystals as spin memory-resistors (memristors) that act differently from the known oxide-based inorganic memristors. These MOCs can have more than <NUM> bits of memory and the fabricated devices are chemically and structurally stable.

A memristor is a nonlinear component with properties that cannot be replicated with any combination of the other fundamental components, combines a persistent memory with electrical resistance. In other words, a memristor has a non-linear resistance that can act as a universal memory that enables logic operations. The device presented in this Example combines a memristor's behavior with multilevel logic.

The CISS effect offers a unique approach for meeting the challenge of simple and small memristor fabrication. Because of the CISS effect, chiral molecules and crystals can act as efficient spin filters. The MOC described in this example consists of Cu-phenylalanine crystals that are chiral. Example <NUM> above showed that these crystals were shown to have good conduction and ferromagnetic properties at room temperature.

D-enantiomers of the amino acid phenylalanine were crystallized with copper ions and characterized by X-ray analysis and circular dichroism (CD) spectroscopy. The asymmetric units of the crystal consist of phenylalanine dimer coordinating a copper atom, and the unit-cell consists of two dimers, as shown in <FIG> show present a high-order assemblies of the crystal viewed along different axes, and <FIG> show scanning electron microscope (SEM) and optical microscope images, respectively.

<FIG> show the absorption and the CD spectra of the crystal, respectively. <FIG> shows the absorption spectra when the crystal is excited with clockwise (RCL) and counter-clockwise (LCL) circular polarized light.

All the electrical measurements were performed in a planar architecture when the device is located on a thermal oxide (SiO<NUM>-<NUM>) p-type silicon wafer. The optical microscope image and the graphic sketch of the right-handed D-enantiomers of phenylalanine MOC crystals located between two gold pads are shown in the inset in <FIG>. This figure also presents the photocurrent through the crystals measured at a bias of 5V, for left or right circular polarized light (<NUM>). As shown, the photocurrent is stronger by about <NUM>% for the right circular polarization, despite that the light absorption at this wavelength is similar for the two circular polarizations (see <FIG>). Therefore, the large dependence of the photocurrent on the light circular polarization results from the preferred spin conductivity.

Example <NUM> showed that conduction through the crystals is spin selective, due to the CISS effect. Since the excitation by circular polarized light results in exciting one spin direction, following the excitation, there is an electron in the excited state with one specific spin and the hole in the ground state has the same specific spin. In accordance with the two-band conduction model, the hole conduction is expected to be improved as a result of the scattering reduction for the same spin. When this spin is the spin preferred for conduction through the chiral system, a large photocurrent is produced. A similar improvement in conductivity after magnetizing the Cu atoms is presented shown in <FIG>. For the opposite circular polarization excitation, the preferred conducted spin faces a spin blockade on the excited Cu ions and its conduction will be suppressed. The Inventors also measured magneto resistance hysteresis at room temperature.

<FIG> shows the temperature-dependent resistance, which indicates that at a low temperature, when the crystal becomes antiferromagnetic, the resistance increases, whereas at a higher temperature, of above about <NUM>, the resistance follows the Arrhenius behavior, as shown in <FIG>. From this plot, the activation energy can be obtained. This activation energy corresponds to the band gap of the material and it was found to be about <NUM>±<NUM> meV, and independent of the current flow. The Inventors found that the produced crystals were very stable under current and observed no deterioration when operating at <NUM> mA for many hours.

In this Example, three different types of devices have been used to study the spin memristor behaviour: a Hall device, a gated device, and a gated device with magnetic leads.

The first configuration studied is a Hall configuration. As shown in <FIG>, the Hall device contains six Au probes for measuring both the Hall and transport properties. The source-drain voltage was swiped from -15V to 15V and back at different rates. The Hall voltage was measured in parallel with the drain-source current, enabling one to correlate spin accumulation with current. The inset in <FIG> shows that memristive behaviour exists when the drain-source voltage is scanned. The nonlinear hysteresis loop of the spin memristor differs from the standard oxide-based memristor. In an oxide-based memristor, the current applied increases the resistance, since the current fills the charge trap states. The device of the present embodiments, in distinction, is based on magnetism induced by the current (similar to the light-induced magnetization explained above). Therefore, the resistance is reduced by applying the current.

The device of the present embodiments exhibits a strong dependence of the hysteresis on the current sweep frequency and the hysteresis decays at a high frequency. This frequency dependence is presented in <FIG>. With a higher sweep rate, the distance between the two hysteresis peaks is reduced.

Note that different devices exhibit similar behaviour, for example, when comparing <FIG> show the drain-source and the Hall voltage hysteresis, respectively, for another device that was used for obtaining the results shown in <FIG>. The Hall voltage response indicates that magnetization is generated when the current is driven. The Hall voltage is always negative, demonstrating that the spin polarization is due to the CISS effect, since the CISS effect generates the same magnetization when the current direction is switched. This is because the sign of the spin transported is reversed when the current direction is flipped. The large correlation between the Hall signal hysteresis and the drain-source hysteresis can be used in some embodiments of the present invention to reduce the device's noise.

Example <NUM> showed that the phenylalanine crystals exhibit ferromagnetic behaviour at room temperature, but the crystals become antiferromagnetic below <NUM>. Therefore, it is expected that a hysteresis that relates to the magnetic properties of the material disappears at low temperatures. The temperature dependence I vs. the V curves of a device is presented in <FIG>. As shown, the hysteresis gradually becomes smaller with decreasing temperature and is almost negligible at <NUM>. Below <NUM>, however, the resistance becomes so high that the current observed is extremely low. This is also consistent with the observations shown in Example <NUM>.

Direct magnetization measurements, as a function of temperature, are presented in <FIG>, along with a scheme of the device (inset). In these measurements, the residue signals from the substrate and the metal electrode were subtracted by deducting the signal obtained for source-drain voltages at <NUM>. When the voltage was kept constant, the temperature was reduced from <NUM> to <NUM> and then restored. With decreasing temperature, the difference in magnetization between the temperatures scanned up and down gets smaller. Note that upon reducing the temperature, the resistance of the device increases, especially at temperatures below <NUM>. Therefore, the current decreases. The observed temperature-dependent hysteresis is consistent with current-induced magnetization. Below <NUM>, the system becomes, partially at least, antiferromagnetic and therefore magnetization is reduced. At temperatures above <NUM>, the increase in magnetization upon cooling is consistent with ferromagnetism. Upon warming, the magnetic moment reduces, but the reduction is partially compensated by an increase in the current, resulting in the increased magnetization.

The current-induced magnetization effect was used to generate a multi-level spin memristor, as shown in <FIG>. The set-up is shown in <FIG>. The bottom gate was used to tune the density of the carriers in the system. The source was a magnetic Ni pad and the drain was an Au pad. A magnetic field of about <NUM> Tesla was applied using a permanent magnet in the direction of the current. The memristor behaviour was controlled by two in-plane magnetization directions: North and South and by random magnetization. In this way, it was possible to inject polarized spins into the crystal and to apply electric potential using the gate. Current versus voltage measurements were performed under a magnetic field and with different gate voltages.

The multi-level logic is shown in <FIG>. The parameters of the levels can be tuned by choosing a different drain-source voltage or gate voltage. Note that the direction of the external magnetic field applied does not coincide perfectly with the direction of the current-induced magnetization in the crystal. Consequently, the hysteresis observed is the largest if no external magnetic field is applied and the magnetic moment is only due to the current-induced magnetization, with no interference of the external magnetic field.

The observed memristor behaviour results from the special properties of the crystal, which combine chirality and ferromagnetism at room temperature. The current through the chiral crystal is spin selective, due to the CISS effect. The spin current induces the magnetization of the unpaired electrons on the Cu+<NUM> ions. Hence, the hysteresis in resistance and non-linearity results from reducing scattering within the crystal, upon the formation of ferromagnetic domains. The copper ions are responsible for the relatively good conduction of the crystals at room temperature. As was observed by calculations, the ions states lie just above the highest lying molecular orbitals (HOMO) and they indicate a barrier of about <NUM> meV for conduction. In addition, as shown in <FIG>, when the crystals are illuminated, the current is influenced by the circular polarization of the light. As a result of all these properties, the conduction through the crystals is susceptible to both electric and magnetic fields, as well as to the spin direction of electrons injected from the magnetic source. This provides a wide range of control parameters for a two-terminal device (<FIG>). These control parameters allow achieving multilevel memrestive logic using simple organic materials (<FIG>).

This Example showed that by using organic materials can be used for fabricating devices with new properties that are stable for a long time at ambient conditions. The ability to combine chirality and magnetism with good conduction makes the crystal of the present embodiments useful for many spintronic applications, particularly devices having a size on the order of tens of nanometers.

Claim 1:
A spin-selective conduction structure (<NUM>), comprising a crystal (<NUM>) having a monolayer (<NUM>) of metal atoms (<NUM>) between two layers (<NUM>, <NUM>) of chiral organic molecules (<NUM>), wherein each metal atom is coupled to two chiral organic molecules, one at each layer, and wherein a chirality of organic molecules in one of said two layers is the same as a chirality of organic molecules in a another one of said two layers.