Search query: Spin selectivity through chiral polyalanine monolayers on semiconductors

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abstract: Electrical generation of polarized spins in nonmagnetic materials is of great interest for the underlying physics and device potential. One such mechanism is chirality induced spin selectivity (CISS) with which structural chirality leads to different electric conductivities for electrons of opposite spins. The resulting effect of spin filtering has been reported for a number of chiral molecules. However, the microscopic mechanism and manifestation of CISS in practical device structures remain controversial; in particular, the Onsager relation is understood to preclude linear response detection of CISS by a ferromagnet. Here, we report direct evidence of CISS in two terminal devices of chiral molecules on the magnetic semiconductor (Ga,Mn)As: In vertical heterojunctions of (Ga,Mn)As/AHPA L molecules/Au, we observed characteristic linear and nonlinear response magnetoconductance, which directly verifies spin filtering by the AHPA L molecules and spin detection by the (Ga,Mn)As. The results constitute definitive signature of CISS induced spin valve effect, a core spintronic functionality, in apparent violation of the Onsager reciprocity. The results present a promising route to semiconductor spintronics free of any magnetic material.
author_names: Tianhan Liu

Xiaolei Wang

Hailong Wang

Gang Shi

Fan Gao

Honglei Feng

Haoyun Deng

Longqian Hu

Eric J Lochner

Pedro Schlottmann

Stephan von Moln'ar

Yongqing Li

Jianhua Zhao

Peng Xiong Department of Physics

Florida State University

State Key Laboratory of Superlattices

Institute of Semiconductors

Chinese Academy of Sciences

Beijing National Laboratory for Condensed Matter Physics

Institute of Metal Physics

College of Physical Sciences

Beijing University of Technology
title: Spin selectivity through chiral polyalanine monolayers on semiconductors
year: 2019

abstract: Recent experiments have demonstrated that the electron transmission yield through chiral molecules depends on the electron spin orientation. This phenomenon has been termed the chiral induced spin selectivity (CISS) effect, and it provides a challenge to theory and promise for organic molecule based spintronic devices. This article reviews recent developments in our understanding of CISS. Different theoretical models have been used to describe the effect; however, they all presume an unusually large spin orbit coupling in chiral molecules for the effect to display the magnitudes seen in experiments. A simplified model for an electron's transport through a chiral potential suggests that these large couplings can be manifested. Techniques for measuring spin selective electron transport through molecules are overviewed, and some examples of recent experiments are described. Finally, we present results obtained by studying several systems, and we describe the possible application of the CISS effect for memory devices.
author_names: Ron Naaman

David H Waldeck
title: Spintronics and chirality: spin selectivity in electron transport through chiral molecules.
venue: Annual review of physical chemistry
year: 2015

abstract: The interaction of low energy photoelectrons with well ordered monolayers of enantiopure helical heptahelicene molecules adsorbed on metal surfaces leads to a preferential transmission of one longitudinally polarized spin component, which is strongly coupled to the helical sense of the molecules. Heptahelicene, composed of only carbon and hydrogen atoms, exhibits only a single helical turn but shows excess in longitudinal spin polarization of about P Z 6 to 8% after transmission of initially balanced left and right handed spin polarized electrons. Insight into the electronic structure, that is, the projected density of states, and the spin dependent electron scattering in the helicene molecule is gained by using spin resolved density functional theory calculations and a model Hamiltonian approach, respectively. Our results support the semiclassical picture of electronic transport along a helical pathway under the influence of spin orbit coupling induced by the electrostatic molecular potential.
author_names: Matthias Kettner

Volodymyr V Maslyuk

Daniel Nurenberg

Johannes Seibel

Rafael Gutierrez

Gianaurelio Cuniberti

Karl-Heinz Ernst

Helmut Zacharias
title: Chirality Dependent Electron Spin Filtering by Molecular Monolayers of Helicenes.
venue: The journal of physical chemistry letters
year: 2018

abstract: Spin based properties, applications, and devices are commonly related to magnetic effects and to magnetic materials. Most of the development in spintronics is currently based on inorganic materials. Despite the fact that the magnetoresistance effect has been observed in organic materials, until now spin selectivity of organic based spintronics devices originated from an inorganic ferromagnetic electrode and was not determined by the organic molecules themselves. Here we show that conduction through double stranded DNA oligomers is spin selective, demonstrating a true organic spin filter. The selectivity exceeds that of any known system at room temperature. The spin dependent resistivity indicates that the effect cannot result solely from the atomic spin orbit coupling and must relate to a special property resulting from the chirality symmetry. The results may reflect on the importance of spin in determining electron transfer rates through biological systems.
author_names: Zuoti Xie

Tal Z Markus

Sidney R Cohen

Zeev Vager

Rafael Gutierrez

Ron Naaman
title: Spin specific electron conduction through DNA oligomers.
venue: Nano letters
year: 2011

abstract: The electron's spin is essential to the stability of matter, and control over the spin opens up avenues for manipulating the properties of molecules and materials. The Pauli exclusion principle requires that two electrons in a single spatial eigenstate have opposite spins, and this fact dictates basic features of atomic states and chemical bond formation. The energy associated with interacting electron clouds changes with their relative spin orientation, and by manipulating the spin directions, one can guide chemical transformations. However, controlling the relative spin orientation of electrons located on two reactants (atoms, molecules or surfaces) has proved challenging. Recent developments based on the chiral induced spin selectivity (CISS) effect show that the spin orientation is linked to molecular symmetry and can be controlled in ways not previously imagined. For example, the combination of chiral molecules and electron spin opens up a new approach to (enantio)selective chemistry. This Review describes the theoretical concepts underlying the CISS effect and illustrates its importance by discussing some of its manifestations in chemistry, biology and physics. Specifically, we discuss how the CISS effect allows for efficient long range electron transfer in chiral molecules and how it affects biorecognition processes. Several applications of the effect are presented, and the importance of controlling relative spin orientations in multi electron processes, such as electrochemical water splitting, is emphasized. We describe the enantiospecific interaction between ferromagnetic substrates and chiral molecules and how it enables the separation of enantiomers with ferromagnets. Lastly, we discuss the relevance of CISS effects to biological electron transfer, enantioselectivity and CISS based spintronics applications.Chiral molecules can filter electrons according to their spin. This chiral induced spin selectivity (CISS) effect can have important applications, such as in spintronics and in enantioseparation. This Review describes the CISS effect, its mechanism and its fascinating applications.
author_names: Ron Naaman

Yossi Paltiel

David H Waldeck
title: Chiral molecules and the electron spin
venue: Nature Reviews Chemistry
year: 2019

abstract: Chirality induced spin selectivity is a recently discovered effect, which results in spin selectivity for electrons transmitted through chiral peptide monolayers. Here, we use this spin selectivity to probe the organization of self assembled a helix peptide monolayers and examine the relation between structural and spin transfer phenomena. We show that the a helix structure of oligopeptides based on alanine and aminoisobutyric acid is transformed to a more linear one upon cooling. This process is similar to the known cold denaturation in peptides, but here the self assembled monolayer plays the role of the solvent. The structural change results in a flip in the direction of the electrical dipole moment of the adsorbed molecules. The dipole flip is accompanied by a concomitant change in the spin that is preferred in electron transfer through the molecules, observed via a new solid state hybrid organic inorganic device that is based on the Hall effect, but operates with no external magnetic field or magnetic material.
author_names: Meital Eckshtain-Levi

Eyal Capua

Sivan Refaely-Abramson

Soumyajit Sarkar

Yulian Gavrilov

Shinto P Mathew

Yossi Paltiel

Yaakov Levy

Leeor Kronik

Ron Naaman
title: Cold denaturation induces inversion of dipole and spin transfer in chiral peptide monolayers
venue: Nature communications
year: 2016

abstract: The combination of photonics and spintronics opens new ways to transfer and process information. It is shown here that in systems in which organic molecules and semiconductor nanoparticles are combined, matching these technologies results in interesting new phenomena. We report on light induced and spin dependent charge transfer process through helical oligopeptide CdSe nanoparticles' (NPs) architectures deposited on ferromagnetic substrates with small coercive force ~100 200 Oe) The spin control is achieved by the application of the chirality induced spin dependent electron transfer effect and is probed by two different methods: spin controlled electrochemichemistry and photoluminescence (PL) at room temperature. The injected spin could be controlled by excitation of the nanoparticles. By switching the direction of the magnetic field of the substrate, the PL intensity could be alternated.
author_names: Prakash Chandra Mondal

Partha Roy

Dokyun Kim

Eric E Fullerton

Hagai Cohen

Ron Naaman
title: Photospintronics: Magnetic Field Controlled Photoemission and Light Controlled Spin Transport in Hybrid Chiral Oligopeptide Nanoparticle Structures
venue: Nano letters
year: 2016

abstract: With the increasing demand for miniaturization, nanostructures are likely to become the primary components of future integrated circuits. Different approaches are being pursued toward achieving efficient electronics, among which are spin electronics devices (spintronics) In principle, the application of spintronics should result in reducing the power consumption of electronic devices. Recently a new, promising, effective approach for spintronics has emerged, using spin selectivity in electron transport through chiral molecules. In this work, using chiral molecules and nanocrystals, we achieve local spin based magnetization generated optically at ambient temperatures. Through the chiral layer, a spin torque can be transferred without permanent charge transfer from the nanocrystals to a thin ferromagnetic layer, creating local perpendicular magnetization. We used Hall sensor configuration and atomic force microscopy (AFM) to measure the induced local magnetization. At low temperatures, anomalous spin Hall effects were measured using a thin Ni layer. The results may lead to optically controlled spintronics logic devices that will enable low power consumption, high density, and cheap fabrication.
author_names: Oren Ben Dor

Noam Morali

Shira Yochelis

Lech Tomasz Baczewski

Yossi Paltiel
title: Local light induced magnetization using nanodots and chiral molecules.
venue: Nano letters
year: 2014

abstract: Recently, the chiral induced spin selectivity in molecular systems has attracted extensive interest among the scientific communities. Here, we investigate the effect of the gate voltage on spin selective electron transport through the \alpha$ helical peptide/protein molecule contacted by two nonmagnetic electrodes. Based on an effective model Hamiltonian and the Landauer B\"uttiker formula, we calculate the conductance and the spin polarization under an external electric field which is perpendicular to the helix axis of the \alpha$ helical peptide/protein molecule. Our results indicate that both the magnitude and the direction of the gate field have a significant effect on the conductance and the spin polarization. The spin filtration efficiency can be improved by properly tuning the gate voltage, especially in the case of strong dephasing regime. And the spin polarization increases monotonically with the molecular length without the gate voltage, which is consistent with the recent experiment, and presents oscillating behavior in the presence of the gate voltage. In addition, the spin selectivity is robust against the dephasing, the on site energy disorder, and the space angle disorder under the gate voltage. Our results could motivate further experimental and theoretical works on the chiral based spin selectivity in molecular systems.
author_names: Ting-Rui Pan

Ai-Min Guo

Qing-feng Sun
title: Effect of gate voltage on spin transport along \alpha$ helical protein
year: 2015

abstract: We show that in an electrochemical cell, in which the photoanode is coated with chiral molecules, the overpotential required for hydrogen production drops remarkably, as compared with cells containing achiral molecules. The hydrogen evolution efficiency is studied comparing seven different organic molecules, three chiral and four achiral. We propose that the spin specificity of electrons transferred through chiral molecules is the origin of a more efficient oxidation process in which oxygen is formed in its triplet ground state. The new observations are consistent with recent theoretical works pointing to the importance of spin alignment in the water splitting process.
author_names: Wilbert Mtangi

Vankayala Kiran

Claudio Fontanesi

Ron Naaman
title: Role of the Electron Spin Polarization in Water Splitting
venue: The journal of physical chemistry letters
year: 2015