bluuebunny/crossref_metadata_2025 huggingface dataset:
An Experimental Study of Thermal Radiation in Low Temperature
Authors: Amano T. , Ohara A. , Yamada T.
Published: March 2014

We have measured the effective emissivity “E” between an aluminum surface of 66–85(K) and the various finished surfaces of 4.3(K). The ratios of E are : E(SUS) : E(SUS polished) : E(copper plating) : E(Al-tape taping) : E(Al-Myler wrapping) = 1.0 : 0.94 : 0.56 : 0.52 : 0.49. The heat transfer “Q” for different multilayer insulation systems between room temperature and liquid nitrogen temperature is also measured. The ratios of Q are : Q(Al) : Q(10-layers) : Q(20-layers) : Q(30-layers) : Q(50-layers) = 1.0 : 0.39 : 0.35 : 0.33 : 0.32.
Drift Performance of D. C. Paramagnetic Salt Thermometers
Authors: Marek D.
Published: March 2014

The drift behavior and long term stability of an ultra high resolution paramagnetic salt thermometer which operates in the vicinity of the lambda transition of 4He have been studied. Various sources contributing to the total drift are analyzed, and new designs are discussed.
Sound Attenuation Peak Around 1 K in 3He–4He Mixtures
Authors: Iwasa Izumi , Fujii Itsuhiro , Ikushima Akira J.
Published: March 2014

Sound attenuation peaks around 1 K have been measured at 10, 30 and 50 MHz in 3He–4He mixtures of the 3He concentration x3=0.013, 0.029 and 0.050 under the saturated vapor pressure. The relaxation time related to the interaction between phonons and 3He quasiparticles has been determined experimentally, and its temperature and 3He concentration dependences agree with the theory of Khalatnikov and Zharkov.
The Bayreuth Nuclear Demagnetization Refrigerator
Authors: Smeibidl P. , Gloos K. , Kennedy C. J. , Mueller R. M. , Pobell F. , Sekowski P. , Singsaas A.
Published: March 2014

In this letter we report on the construction and operation of the new nuclear refrigerator at the University of Bayreuth. It contains two Cu stages of 103.5 moles in 8 Tesla and 2 moles in 9 Tesla, respectively. After demagnetization the first stage has cooled a Pt-NMR thermometer in the field free experimental region to 15 µK. The large heat capacity of the stage has enabled us to hold this low temperature for 50 h without any sign of warming. In a preliminary test under nonideal conditions the second stage has cooled another Pt-NMR thermometer in the high field region to 12 µK.
A Nuclear Demagnetization Cryostat and 3He-4He Dilution Refrigerator
Authors: Borovik-Romanov A. S. , Bunkov Yu. M. , Dmitriev V. V. , Mukharsky Yu. M.
Published: March 2014

Construction and performance of a 3He-4He dilution refrigerator used for precooling of a copper nuclear stage is described. Design and parameters of the nuclear demagnetization cryostat, which is used to study superfluid 3He at temperatures down to 0.168 mK, are given.
A Novel Top-Loading 20 mK/15 T Cryomagnetic System
Authors: Reinders P. H. P. , Springford M. , Hilton P. , Kerley N. , Killoran N.
Published: March 2014

A new type of dilution refrigerator is described with easy loading of the sample directly into the dilute phase in the mixing chamber. Electrical, optical and mechanical services to the sample are readily incorporated and electrically insulating tails allow the use of high and variable magnetic fields. A sample temperature of 20mK in a field of 15T has been achieved.
Noise Thermometry below 4 K
Authors: Reesink A. L. , Steuten H. M. , Bremer J. , Durieux M.
Published: March 2014

A noise thermometer with a manganin noise resistor of 10-4 - 10-5 Ω and an rf SQUID for measuring the noise signal is described. Preliminary results, mainly between 4 K and 0.5 K, are given. The thermometer is presently used for setting up a temperature scale below 0.5 K.
Observation of Phase Slips in Spin Supercurrents in 3He–B
Authors: Borovik-Romanov A. S. , Bunkov Yu. M. , Dmitriev V. V. , Mukharsky Yu. M.
Published: March 2014

We have observed spin supercurrents which transport the longitudinal magnetization of 3He–B through a narrow channel connecting two chambers filled with superfluid 3He–B. The magnetization of 3He–B in these chambers and in the channel is tilted by the angle 104° and processes. The magnitude of the spin supercurrent is determined by the difference in the precession phase angle between the ends of the channel. The critical supercurrent is measured when phase slips take place.
Quantum Oscillations in the Phonon Scattering by a 2-DEG of a Si-MOSFET
Authors: Rampton V. W. , Newton M. I. , Kent A. J. , Carter P. J. A. , Hardy G. A. , Russell P. A. , Challis L. J.
Published: March 2014

Phonon scattering by a 2-DEG has been studied using ballistic heat pulses. Heat pulses generated by a gold thin-film resistance heater have been detected by a CdS bolometer after passing through a 2-DEG in the inversion layer of a Si-MOSFET held at 4.2K. The detected ballistic phonon pulses have been examined as a function of gate voltage and applied magnetic field. At a magnetic field of 5T the pulse height oscillates with an amplitude of about 0.5% of the initial pulse height and with a period which is identical to the period of Shubnikov-de Haas oscillations in electrical conductivity.
Vortices in 3He–A in Restricted Geometries
Authors: Hakonen P. J. , Nummila K. K.
Published: March 2014

We have studied vortices in 3He–A between a stack of plates with about 20 µm spacing and within an array of long cylinders of 0.5 mm diameter. Taking advantage of localised surface spin-wave modes, trapped by the \hatℓ texture near the walls, we have determined the critical velocity for vortex formation as well as the pinning velocity for vortices in the plate geometry. In 0.5-mm cylinders vortices are similar to those in the bulk liquid but a broad hysteresis in the number of vortices (1-4/tube) is observed when the cryostat is accelerated or decelerated.
Focusing of Negative Ions by Vortices in Rotating 3He–A
Authors: Nummila K. K. , Simola J. T. , Korhonen J. S. , Skrbek L.
Published: March 2014

We have studied continuous vortices in rotating 3He–A in the high external magnetic field H = 28.4 mT. The time-of-flight of negative ion pulses, drifting parallel to \vecΩ, increases considerably and the pulses lengthen drastically in rotating liquid, compared with Ω=0. This is caused by an interaction between the ions and the \hatℓ texture in the soft cores of the vortices. The interaction is mediated by the anisotropic ion mobility: \vecv=µ⊥\vecE-Δµ(\vecE·\hatℓ)\hatℓ. The (Ω, T)-dependence of the retardation can be described by a model that assumes focusing of ions into the vortex cores, where Ions focused into vortex cores drift approximately the mobility is lower than in the bulk liquid, parallel to \hatℓ.
Electron-Phonon Effects in Heavy Electron Systems
Authors: Lüthi B.
Published: March 2014

Electron-phonon effects are briefly discussed. Details can be found in the list of references.
Equilibrium and Non-Equilibrium Dynamics of Short-Range Spin-Glasses
Authors: Fisher Daniel S.
Published: March 2014

A recently developed theoretical description of the statics and dynamics of short-range spin glasses is summarized. The main features can be described in terms of droplet excitations and the dynamics of domain walls. Predictions for equilibrium properties, the global structure of the phase diagram, and non-equilibrium dynamic effects are briefly discussed.
High Tc Superconducting States in Organic Metals, β-(BEDT-TTF)2X
Authors: Tokumoto Madoka , Anzai Hiroyuki , Murata Keizo , Kajimura Koji , Ishiguro Takehiko
Published: March 2014

Superconductivity in a series of isostructural organic metals, β-(BEDT-TTF)2X, where X=I3, I2Br, IBr2, (I3)1-x
(IBr2)
x
, (IBr2)1-x
(I2Br)
x
and (I2Br)1-x
(I3)
x
, has been studied. The entire scheme of phase diagram connecting the two superconductors, one (I3 salt) with high- and low-T

c
states and the other (IBr2 salt) with intermediate T

c
, is described. Through the observation of stepwise anomaly in dR/dT, it was found that the suppression of the incommensurate lattice modulation in the I3 salt can be realized by alloying with IBr2 salt. The effect of alloying on the superconductivity was found to show marked differences in the vicinity of each different superconducting states. Strong correlation between the superconductivity and residual conductivity was found, leading to a systematic understanding of the whole scheme in terms of Anderson localization. Alloying and proton irradiation were found to show completely different effects on the pressure dependence of T

c
, indicating that the mechanism of T

c
reduction in the latter is not the same.
The Prospect of Superconductivity at Very High Temperatures
Authors: Chu C. W. , Bechtold J. , Gao L. , Hor P. H. , Huang Z. J. , Meng R. L. , Wang Y. Q.
Published: March 2014

The present status of superconductivity at very high temperatures, i.e. substantially higher than 100K, is summarized and examined. Possible future steps toward very high temperatures are suggested and discussed.
Liquefaction of Highly Polarized 3He
Authors: Nacher Pierre-Jean , Leduc Michèle , Tastevin Geneviève , Wiesenfeld Laurent , Laloe Franck
Published: March 2014

Fast cooling of a 3He gas polarized by laser optical pumping (up to 50% or more) leads to the condensation of a droplet of liquid 3He↑. The magnetization of the liquid has been observed to be in equilibrium with that of the vapour, and to decay with a time constant of 6 minutes.
Application of Atomic Hydrogen at Low Temperatures: The Recirculating Cryogenic Hydrogen Maser
Authors: Hardy W. N. , Hürlimann M. D. , Cline R. W.
Published: March 2014

Conventional hydrogen masers are the most stable of all atomic clocks with stabilities Δf/f of better than 10-15 for measuring times τ of 103 sec. A new generation of cryogenic hydrogen masers has the potential to improve this figure by 2 to 3 orders of magnitude. Here we describe how research on spin-polarized atomic hydrogen led to the construction at the University of British Columbia of a uniquely cryogenic hydrogen maser. In this maser, which operates at 0.5K and uses liquid helium coated walls throughout, H atoms circulate back and forth between a microwave pumped state selector and the maser cavity. The measurement of the frequency stability is presently limited by the frequency stability of the available references, but values of Δf/f<10-13 for τ=1 sec have been recently established. The successful development of rather different cryogenic masers at other institutions will also be discussed.
The Viscosity of Spin Polarized 3He–4He Mixtures
Authors: Church R. J. , OwerS-Bradley J. R. , Main P. C. , Hampson T. M. M. , McHale G. , Bowley R. M.
Published: March 2014

We report measurements of the viscosity of a 0.1% 3He–4He mixture obtained from the damping of second sound at low temperatures and in a magnetic field of 10T. The damping of second sound arises from the bulk viscosity, the surface viscosity and from losses on reflection from the ends of the cavity. From the frequency dependence of the widths of the resonance we obtain the viscosity accurate to 3%. The viscosity is observed to increase when a field is applied and this increase is in agreement with the recent prediction of Hampson et al. who calculated changes in the transport properties of 3He–4He mixtures for temperatures of order the fermi temperature.
Transverse Field in the Sherrington-Kirkpatrick Model
Authors: Yamamoto Tetsuya , Ishii Hiroumi
Published: March 2014

Quantum effect due to a transverse field Δ in the Sherrington-Kirkpatrick spin.glass model is studied on (i) the phase diagram in the T–Δ plane, and (ii) physical quantities in the spin glass phase. For the latter purpose at T=0, systems with finite number of spins are investigated numerically by mean field approach. A naive mean field theory is examined by the argument on the largest eigenvalue of the random matrix. An attempt is made to improve the mean field calculation.
Equivalent Flux Noise in a YBa2Cu3Ox rf SQUID
Authors: Zimmerman J. E. , Beall J. A. , Cromar M. W. , Ono R. H.
Published: March 2014

We have measured the noise in flux-locked rf SQUIDs made of bulk YBa2Cu3O
x
both in a He cooled cryostat and in liquid nitrogen (LN2). Our best results at 75 K show a spectral density of the equivalent flux noise equal to 4.5×10-4φ0/√H
z. There is considerable variation in the performance of SQUIDs made from nominally similar material.
Function of Plasmons in Superconductivity of Cuprates
Authors: Ruvalds J. , Sheng Q. G.
Published: March 2014

The spectrum of acoustic plasmons in copper oxide alloys is shown to enhance the superconducting transition temperature providing that the Fermi energy intersects two energy bands whose maxima are well separated in energy. Comparison to the observed infrared structure provides a distinction
between high TC and normal metal alloys.
Sound Velocity and Ultrasonic Absorption in High-Tc-Superconductors
Authors: Müller V. , Groot K. de , Maurer D. , Roth Ch. , Rieder K. H. , Eickenbusch E. , Schöllhorn R.
Published: March 2014

We report on strong hysteresis effects in the temperature dependence of the longitudinal ultrasonic attenuation and group-velocity in YBa2Cu3O7.
The Influence of Irradiation-Induced Defects on the Superconductivity of YBa2Cu3O7
Authors: Egner B. , Geerk J. , Li H. C. , Linker G. , Meyer O. , Strehlau B.
Published: March 2014

Thin superconducting films of YBa2Cu3O7 have been irradiated at 293 K and 77 K with H, He and Ar ions. Independent on the mass and the energy of the incident ions the Tc reduction below 4.2 K occurred in the region between 2×10-3 and 1.6×10-2 displacements per atom (dpa). For dpa values greater than 4×10-3 (0.2 eV/atom) a strong increase of the resistance was noted indicating a metallic to insulating transformation. The orthorhombic to tetragonal phase transformation occurred between 0.01 and 0.03 dpa while the transformation into the amorphous phase was observed at about 0.1 dpa after He irradiation at 77 K. The damage mechanisms which are responsible for all this changes are discussed.
Magnetic Trapping of Spin-Polarized Atomic Hydrogen
Authors: Hess Harald F. , Kochanski Greg P. , Doyle John M. , Masuhara Naoto , Kleppner Daniel , Greytak Thomas J.
Published: March 2014

We have confined over 5×1012 atoms of hydrogen in a static magnetic trap. The atoms are loaded into the trap by precooling with a dilution refrigerator. At operating densities near 1×1013 cm-3 the gas is observed to be electron- and nuclear-polarized in the uppermost hyperfine state. The long lifetime of the trapped gas (over 20 minutes) suggests that it is thermally decoupled from the wall and has evaporatively cooled to a temperature of about 41 mK. The residual decay of the gas density is consistent with spin relaxation induced by dipolar interactions between atoms.
Resonant Recombination of Spin-Polarized Atomic Hydrogen at Low Temperatures
Authors: Reynolds M. W. , Shinkoda I. , Cline R. W. , Hardy W. N.
Published: March 2014

We describe calculations of the predissociation of the (ν,J) = (14,4) level of molecular hydrogen and its contribution to the recombination of spin-polarized atomic hydrogen.
Reflection of 4He Atomic Beams from Films of Superfluid 4He on Glass and Mica
Authors: Mukherjee S. , Candela D. , Edwards D. O. , Kumar S.
Published: March 2014

We have measured the reflection coefficient of 4He atoms from films of super fluid 4He on glass and mica. The measurements were made as a function of the momentum of the atoms and the film thickness. We observed specular reflection from the glass substrate only for a thick (232Å) film, and from the mica for both a thin (34Å) and a thick (232Å) film. No inelastic scattering is observed. The thin film has a much smaller reflection coefficient than the thick film.
Quantum Effect on Helium Adsorbed in Y Zeolite
Authors: Kato H. , Wada N. , Miyamoto S. , Ito T. , Watanabe T.
Published: March 2014

Heat capacities of 4He adsorbed in Y zeolite, in which there is a three-dimensional(3D) network of channels of only about 10A in diameter, have been measured at 0.6<T<15K as a function of the adsorbed amount n. At nnc, the heat capacities are well described with sum of two parts, αT2+β or αT2+γT where α, β and γ are constants depending on n. This result is interpreted in terms of the coexistence of a 2D solid and a gas or a liquid in the small channels.
A Renormalization Group Study for 4He and 3He Adsorbed on Graphite
Authors: Mello E. V. L. de
Published: March 2014

Migdal-Kadanoff real space renormalization group transformations are studied for two microscopic models, the Potts lattice gas and the Potts spin model. The resulting global phase diagrams are analyzed and subspaces are applied to 3He and 4He adsorbed on graphite. The obtained temperature versus density diagrams are compared to the available data and used to discuss helium-helium interaction and to predict possible phases in the low temperature regime.
Heat-Capacity Measurements of Thin 4He Films in Porous Silica-gel Glass
Authors: Finotello D. , Wong A. , Gillis K. A. , Awschalom D. D. , Chan M. H. W.
Published: March 2014

We report precision heat capacity results of submonolayer and near monolayer 4He films adsorbed in porous silica-gel glass. Measurements were performed down to 0.1 K on films up to 26 µmole/m2. These coverages are below the critical value for superfluid onset and thought to be localized and solid-like. A coverage dependent heat capacity anomaly near 0.25 K was found, indicating a possible phase transition.
Exchange in 2-d Solid Helium 3–A T
2 Study
Authors: Cowan Brian , El-Nasr Laila Abou , Fardis Michael , Richards M. G.
Published: March 2014

We present spin-spin relaxation time measurements for helium-3 adsorbed on grafoil in the solid phase. Spin-lattice relaxation measurements have already been analysed and the quantum exchange frequency estimated. Whereas it is only the internuclear dipolar interaction that mediates spin-lattice relaxation, for spin-spin relaxation both dipole dipole and the internal demagnetising fields of the graphite make a contribution. By analysing the frequency dependence of the relaxation time we have distinguished the dipole-dipole part: the frequency independent contribution. This has been analysed to give a measure of the exchange frequency in substantial agreement with that from T
1 measurements.
NMR Study of 3He Adsorbed in High-Silica Zeolites and AlPO4–5
Authors: Deguchi Hiroyuki , Moriyasu Yoshitaka , Amaya Kiichi , Kitaoka Yoshio , Kohori Yoh , Terasak Osamu , Haseda Taiichiro
Published: March 2014

The nuclear susceptibility χ, spin-lattice relaxation time T1 and spin-spin relaxation time T2 of 3He in high silica zeolites and AlPO4–5 have been measured at temperatures below 1.5 K. The behavior of χ(T) of adsorbed 3He depends both on the diameter and structure of the channel pores of the adsorbent. They give the temperature dependence almost alike the Fermi fluid. Only one exception is found in the case of 3He in ZSM-23 which consists of a bundle of very narrow one-dimensional (1D) channel. The χ(T) of 3He obeys Curie's law dawn to 0.1 K.
Magnetic Coupling of 3He Films with Protons in Nuclepore
Authors: Swanson D. R. , Candela D. , Edwards D. O.
Published: March 2014

We have measured the coupling between 3He nuclei and protons in a Nuclepore substrate. It was obtained from the effect of the 3He on the proton-lattice relaxation time at a Larmor frequency of 10 MHz in the temperature range 1.3 to 4.2 K. The coupling is approximately 100 times weaker than that measured by Friedman, Millet and Richardson between 3He and 19F in fluorocarbon beads.
Studies of the Solid/Super fluid 4He Interface with Fourth Sound, Heat Capacity, and 3He Concentration
Authors: Brosius T. , Finotello D. , Maynard J. D. , Chan M. H. W.
Published: March 2014

Our research involves studies of the solid/super fluid 4He interface for multilayer solid 4He on graphite using both fourth sound and heat capacity techniques. In the case of fourth sound the effects of small concentrations of 3He on the interface susceptibility have been measured. Heat capacity measurements determined an upper limit for the criticality of the layering transitions.
Thermal Resistance between Enhanced Nuclear Spins in TmVO4 and Liquid 3He
Authors: Mizutani Naoki , Suzuki Haruhiko , Ohtsuka Taiichiro
Published: March 2014

We have measured the thermal resistance between hyperfine enhanced nuclear spin system of Tm in TmVO4 and liquid 3He, and also 5% 3He–4He mixture in the temperature range between 8mK and about 50mK. For a large single crystal the measured thermal resistance can be explained by the acoustic mismatch theory. For small single crystals and powder specimen, the measured thermal resistance can be understood by the spin-lattice relaxation time of Tm nuclear spin.
Boundary Resistance between PrNi5 and Liquid 3He
Authors: Ytterboe S. N. , Saundry P. D. , Friedman L. J. , Gould C. M. , Bozler H. M.
Published: March 2014

We have measured the steady state thermal conduction between. 3He and PrNi5. The PrNi5 sample consisted of 40 µm particles, which were sufficiently large so that the 3He quasiparticle mean free path was not size limited. The sample was heated with eddy currents and the internal temperature was monitored using the susceptibility of the PrNi5. Our results show that the boundary conductance follows T2 between 2 - 15 mK. We also observed a ∼ 3.5 times increase in the conductance as the applied field was increased from 0 to 400 gauss, but no dependence on pressure or the presence of superfluid. While the field dependence cannot be explained, the
temperature dependence is that expected for a magnetic spin glass.
The Temperature Dependence of Phonon-Atom Evaporation in Liquid 4He
Authors: Baird M , Richards B , Wyatt A. F. G.
Published: March 2014

Quantum evaporation at normal incidence is found to be very temperature dependent between 0.1 and 0.2 K. It is shown that this is mainly due to the phonon-atom rather than the roton-atom component. These results are qualitatively explained by the difference in scattering of high energy phonons and rotons by the thermal phonons. This experiment provides an effective way of studying 4 phonon processes which hitherto have been inaccessible.
Structure Factor of 3He–4He Mixtures
Authors: Sridhar R. , Shanthi A.
Published: March 2014

The excitation spectrum of dilute solutions of 3He in superfluid 4He is evaluated by solving the equation of motion of a suitably constructed excitation operator under the Random Phase Approximation (RPA). The spectrum has two branches. By assuming that the first few moments of the dynamic form factor are saturated by these two branches alone, an integral equation is obtained for the structure factor S(k) which besides displaying the usual features expected of it, bears a close resemblance to experimental results.
Theory of Ferromagnetic State of HCP Solid 3He for Pair, Triple and Quadruple Spin Exchange Interaction. I Spin Wave Theory
Authors: Iwasaki Tomio , Soda Toshio
Published: March 2014

There are two sublattices in hcp solid 3He in spite of the ferromagnetic state, because the hexagonal close-packed structure consists of two interpenetrating simple hexagonal Bravais lattices. The spins in each sublattice, and the multiple-exchange Hamiltonian including the most important two, three and four-particle exchange processes for the hcp phase of solid 3He are expressed in terms of Bose operators al, and bm by the method of Holstein and Primakoff. The eigen-energies of the spin wave obtained and we find an optical magnon branch besides the acoustic magnon branch. We calculate the temperature dependence of the order parameter , the specific heat, and other physical quantities by the method of the spin wave theory.
Nonferromagnetic Nuclear Magnetic Ordering in a Metallic Hyperfine Enhanced Nuclear Magnet PrSe
Authors: Kubota M. , Fischer K. J. , Mueller R. M.
Published: March 2014

The AC susceptibility of a PrSe single crystal sample, a metallic fcc Hyperfine Enhanced Nuclear Magnet, was measured down to 100 µK. A sharp peak indicating a nonferromagnetic transition was observed at 0.5 mK, for the first time in a metallic HENM. The obtained Weiss temperature |θ| coincides with the π peak temperature Tn and the susceptibility below Tn stays constant at high value.
Magnetostriction at the Nuclear-Ordering Transition of PrCu6
Authors: Andersen P. , Weyhmann W.
Published: March 2014

We have observed magnetostriction in the vicinity of the magnetic phase ordering temperature of 2.5 mK as the sample is demagnetized. The sample lengthens as the field is reduced from 200 to 4 mT such that Δℓ/ℓ∼3×10-8.
Crystal-Field Effect on the Electrical Magnetoresistivity of PrNi5
Authors: Reiffers Marián , Flachbart Karol
Published: March 2014

It is shown that the observed decrease of the magnitude of the measured magnetic field dependences of the electrical magnetoresistivity of PrNi5 up to 7 T in the temperature range 11–16 K is a manifestation of the occupation of the first excited crystal-field (CEF) energy level of Pr-ions. Fitting the experimental curves magnetic field and temperature dependences of the molecular field parameter are obtained. The role of the magnetic excitons is discussed.
High Energy Neutron Spectroscopy of Compressed Solid Para-Hydrogen
Authors: Herwig K. W. , Schmidt M. C. , Gavilano J. L. , Simmons R. O.
Published: March 2014

The deep inelastic neutron scattering study of solid hydrogen at 12 K at a molar volume of 23.0 cm3 by Langel et al. has been extended to 19.5 K para-hydrogen samples compressed to molar volumes of 21.2, 19.5, and 18.3 cm3, respectively. In each case, inelastic scattering peaks were observed at energy transfers a) shifted due to the molecular translational recoil energy plus internal rotational excitation and b) broadened due to the translational motion of the initial single-particle ground state. The data are analyzed directly to yield the average kinetic energy <K
E> of the ground state center-of-mass translational motion as a function of molar volume in this quantum solid. Over a 20% decrease in molar volume, <K
E> values increase from 76±9 to 141±9 K. These are compared to indirect measurements.
Tunneling of HD Impurities in Solid Hydrogen
Authors: Edwards C. M. , Cho S. I. , Zhou D. , Sullivan N. S.
Published: March 2014

Measurements of the transverse nuclear spin relaxation times T2 of HD impurities in solid hydrogen have been carried out at low temperatures to test for quantum tunneling of the impurities in a para-H2 matrix. The motion of the HD impurities is believed to be similar in nature to the exchange of atoms in dense hcp 3He. We compare the observed density and temperature dependence of T2 with that predicted by the quantum tunneling model.
Single-Particle Dynamics in the Anderson Lattice
Authors: Fedro A. J. , Dunlap B. D.
Published: March 2014

We present a theory for the single particle dynamics of the U→∞ Anderson lattice using a projection operator which projects out of any operator its exact thermal average in the space of single particle excitations and is capable of handling the complex f statistics properly. It is exact in the large degeneracy limit and gives a dynamically renormalized hybridization and f level energy. In addition, we find self-energy corrections from the on-site c-f exchange and intersite RKKY exchange induced by the correlation which are absent in other truncation treatments and lead to competition between on-site screening and magnetic effects.
Nucleation in Superheated 3He
Authors: Nishigaki Kazu , Saji Yoshiro
Published: March 2014

The superheating of liquid 3He has been carefully measured by means of the continuous heating of a liquid specimen in a small glass capillary. Experiments covered the pressure range 0.05 to 0.85 atm. Maximum superheating temperatures (Ts) obtained were compared with the prediction from the fluctuation theory of homogeneous nucleation. It was found that the agreement between the theory and experiment on 3He was satisfactory. Analysis of the Ts data with respect to the scaled pressure and temperature confirmed the quantum effects in the superheating limit. The surface tension for critical nucleus bubbles was also determined using the experimental Ts data and homogeneous nucleation theory.
The Loop-Expansion Method in Anderson Model
Authors: Koyama Tomio , Tachiki Masashl
Published: March 2014

The loop-expansion method is applied to a study of the dynamical properties in single impurity Anderson model. The Dyson equations for the f-electron and spin-fluctuation Green's functions are expressed in terms of fully renormalized quantities. We solve the Dyson equations by means of the expansion in powers of a renormalized coupling constant and obtain the f-electron density of states and the dynamical susceptibility. The result leads to the consistent understanding for the Kondo system in the low energy region.
Fermi Surface of Ce-Monopnictides in Various Magnetic Ordered States
Authors: Sakai Osamu , Kaneta Yasunori , Kasuya Tadao
Published: March 2014

Band structure calculations for the ferro- and ferrimagnetic phases of CeSb and CeBi are made based on the p-f mixing model and by including the full treatment of the anisotropic d-f exchange interaction in Ce ion. Calculated results well correspond to the Fermi surfaces observed by the de Haas van Alphen experiments. The band which hybridizes most strongly with the occupied f-states has not been observed. The mass enhancement factor for this band due to the scattering with magnon like modes is calculated to be about 11.6. This is consistent with the heavy fermion character of the band expected from low temperature specific heat measurement.
Analytic Calculation of Momentum Distributions and Ground State Energies of Correlated Fermions with the Gutzwiller Wave Function
Authors: Metzner Walter , Vollhardt Dieter
Published: March 2014

A new analytic approach is discussed which allows for an exact evaluation of ground state properties of correlated fermions in terms of the Gutzwiller variational wave function in d = 1. The results are applied to the Hubbard model. The approach may also be used to investigate higher dimensional systems.
Nonuniversal Critical Behavior along the λ-line of 4He
Authors: Schloms R. , Eggers J. , Dohm V.
Published: March 2014

An accurate representation of the renormalization-group (RG) β-function of the Ginzburg-Landau Hamiltoian is given. The nonuniversal parameters of the theory are determined from a few data points of the specific heat above Tλ. Application to the specific heat below Tλ and to the Landau-Placzek ratio of scattered light explains the measured nonuniversal temperature and pressure dependence of these quantities without adjustable parameters.
Dynamical Spin-Susceptibility in Heavy Fermion Systems
Authors: Tachiki Masashi , Takahashi Saburo , Koyama Tomio
Published: March 2014

The dynamical spin-susceptibility of f-electrons in the Anderson lattice is theoretically studied in connection with neutron inelastic-scattering experiments in heavy fermion compounds. The dynamical susceptibility was calculated by using the theory of Anderson lattice formulated by Koyama and Tachiki. The functional form of χF''/(q,ω)/ω, χF''/(q,ω) being the imaginary part of the f-electron susceptibility, is well approximated by a simple Lorentizian form, and its half width remains finite even for q → 0 and decreases with q. This result is consistent with the results of the neutron scattering experiments which observed the spin fluctuations of f-electrons in CeCu6.
Anisotropic Transport Properties of CeAl3
Authors: Jaccard D. , Cibin R. , Jorda J. L. , Flouquet J.
Published: March 2014

CeAl3 single crystals of millimetric size have been grown and resistivity measurements ρ(T) have been performed with the current I applied either parallel or perpendicular to the c axis of the hexagonal structure. Along both directions the maximum of resistivity is observed at ∼35 K but ρmax is larger by a factor of three for I⊥c than for I//c.
Near the Kondo temperature the resistivity for I//c shows a break without corresponding anomaly in the other direction. Below 0.3 K, T2 laws are roughly followed but T3 behavior are rather observed for 0.5<T<1 K. The residual resistivity ρo∼10µΩcm is still larger than that measured for good polycristalline samples.
Anomalous Hall Effect in Heavy Fermion Substances
Authors: Ōnuki Yoshichika , Yamazaki Takashi , Omi Takehiko , Shibutani Kazuyuki , Komatsubara Takemi , Umezawa Ado , Kwok Wai K. , Crabtree George W. , Hinks David G.
Published: March 2014

The Hall coefficient of the heavy fermion compounds CePd3, CeCu2Si2, CeAl3, CeCu6, URu2Si2 and UCu5 manifests an extremely large positive value due to skew scattering by Kondo sites. The Hall coefficient increases with decreasing temperature, making a maximum and decreases steeply. At low temperatures it becomes constant, suggesting a band of heavy electrons.
Magnetic and Transport Properties of New Kondo Compounds CeTIn (T=Ni, Pd and Pt)
Authors: Fujii H. , Uwatoko Y. , Akayama M. , Satoh K. , Maeno Y. , Fujita T. , Sakurai J. , Kamimura H. , Okamoto T.
Published: March 2014

Measurements of magnetic susceptibility, electrical resistivity and thermoelectric power have been made on the CeTIn system (T=Ni, Pd and Pt) with the hexagonal Fe2P-type structure. The results suggest that CeNiIn is an intermediate valence compound with Kondo-like anomalies in resistivity ρm(T), and CePdIn is a heavy fermion compound with doubie-peak structures in both ρm(T) and S(T) and exhibits an antiferromagnetic order at TN=1.8 K, whereas CePtIn is a heavy fermion peak in ρm(T) and shows no magnetic and superconducting transitions.
He II Reservoir Heating to the Lambda Point Vicinity: Superheating Effects
Authors: Frederking T. H. K. , Yuan S. W. K. , Simanjuntak Herbert
Published: March 2014

Fluid state trajectories resulting from a step input in power to a He II reservoir, near zero net mass flow, during slow quasi-steady heating have been investigated for normal fluid “outflow” via a duct. The latter is a capillary (diameter range 1 to 100 µm) which connects the reservoir to a main bath. The results obtained for small diameters rule out the possibility of superheating of He II beyond the He II-He I equilibrium state boundary (lambda line), in agreement with the Landau theory of higher order phase transitions.
Single Crystal Study of Heavy Fermion Ce–Si System –Ground State and Magnetic State–
Authors: Sato Nobuya , Sera Masafumi , Torizuka Kiyoshi , Kohgi Masafumi , Sawada Anju , Satoh Takeo
Published: March 2014

In order to get further insight into the ground state energy level of CeSi
x
system, thermal expansion measurements have been performed for single crystalline CeSi1.86 and CeSi1.70. The results support the T7-like ground doublet which was conjectured from the susceptibility analysis. For CeSi1.70, the existence of the weak antiferromagnetic modulation found by neutron diffraction, has been studied with the magneto-caloric effect measurements to obtain the T-H phase diagram.
Anomalous Ferromagnetism in the Dense Kondo System Ce(Rh1-xCox)3B2
Authors: Yu H. , Ku H. C.
Published: March 2014

Information on the nature of the anomalous ferromagnetic state and paramagnetic Kondo state of CeRh3B2 is gained by studying the evolution of the crystallographic, magnetic, and transport properties across the pseudoternary compounds Ce(Rh1-x
Co
x
)3B2. Unit cell volume variation with Co concentration parameter x indicates that the valence of Ce is increasing from a nearly trivalent value in the Rh-rich region to a high value for x > 0.3 and saturates around x ≈ 0.5. The destruction of ferromagnetism for x > 0.5 thus goes hand in hand with the delocalization of the Ce magnet moment.
Vortices and the Super fluid λ-Transition
Authors: Williams Gary A.
Published: March 2014

An initial model of the superfluid λ-transition is constructed using vortex-ring excitations, as originally suggested by Onsager and Feynman. A real-space renormalization technique generates a screened vortex energy and core size, and gives rise to a transition where rings of infinite diameter are excited as the superfluid density approaches zero at Tc. Although the model satisfies the Josephson hyperscaling relation, it is not yet a complete theory: the superfluid density exponent is v=0.53, and does not match the known value v=0.67.
Magneto-Roton in an Ultra Quantum Crystal: Field Induced Spin Density Wave Phases
Authors: Lederer Pascal , Poilblanc Didier , Montambaux Gilles
Published: March 2014

Collective modes in the Ultra Quantum Spin Density Wave Phases exhibit Goldstone bosons and roton like energy minima at wave vectors which are quantised in terms of the inverse magnetic length. Those energies are well below the single particle energy gap. Field Induced Spin Density Wave Phases are a new type of electron-hole condensate, an Ultra Quantum Crystal.
Effects of Higher Order Energy Gaps of Field Induced Spin Density Waves in Bechgaard Salts
Authors: Chen Liang , Maki Kazumi
Published: March 2014

As is well known the quasi-particle spectrum of a field induced spin density wave (FISDW) consists of a series of energy gaps. When only the dominant single gap is included the thermodynamic properties of a FISDW are same as a BCS superconductor. We study here the effects of higher order gaps on the thermodynamics and the Hall conductivity of a FISDW. First, we show that the jumps in the specific heat at the FISDW transition deviate strongly from the BCS value. Second, we examine the Hall conductivity σ
x
y
in the vicinity of T=T
c
. Inclusion of the multigap structure results in σ
x
y
, which changes almost stepwise as a function of magnetic field, which resembles the quantum Hall effect. However unlike the quantum Hall effect, σ
x
y
increases linearly in (1-T/T

c
) in the vicinity of the transition temperature and furthermore does linearly with l the electron mean free path.
Spin-Peierls State vs Antiferromagnetic State in Quasi-One-Dimensional Heisenberg Antiferromagnet
Authors: Inagaki Satoru , Fukuyama Hidetoshi
Published: March 2014

The competition between the spin-Peierls state and the antiferromagnetic Néel state in the quasi-one-dimensional Heisenberg antiferromagnet is discussed at zero and finite temperatures on the basis of the phase Hamiltonian, which takes proper account of the quantum nature of the one-dimensional spins. On lowering the temperature three types of the phase transitions occur depending on the relative strength of the weak interchain exchange interaction to the spin-lattice coupling.
Noise-Induced Nonlinear Modes in Driven Charge-Density-Wave Systems
Authors: Konno H.
Published: March 2014

The feasibility of bispectral analysis for the charge-density-wave (CDW) conduction noise is proposed. The bispectral patterns of the intermittent sequence obtained from the stochastic models for CDW systems are displayed. Noise-induced non-linear modes due to the interaction between the fluctuating force and the non-linear potential are exemplified. It is demonstrated that the bispectrum is a supplementary tool to characterize the noisy, chaotic current fluctuations in driven charge-density-wave systems.
Electron Tunneling Study of NbSe3
Authors: Ekino Toshikazu , Akimitsu Jun
Published: March 2014

The two CDW energy gaps of NbSe3 were measured by means of the point contact tunneling technique. The peak to peak values of energy gaps at T=4.2K are·typically 2ΔH≃180 mV and 2ΔL≃73 mV from the NbSe3-Au junction, where ΔH and ΔL correspond to the higher CDW transition temperature TH=145K and lower one TL=59K, respectively. From these values, we obtained that 2ΔH/kTH=14.4 and 2ΔL/kTL=14.3, which are much larger than the DCS value.
Measurement of Local Density of States by Scanning Tunneling Spectroscopy at Low Temperature
Authors: Bando Hiroshi , Tokumoto Hiroshi , Mizutani Wataru , Endo Kazuhiro , Wakiyama Shigeru , Watanabe Kazutoshi , Kajimura Koji
Published: March 2014

A scanning tunneling microscope (STM) with a capability of spectroscopic measurement for operation for 300 K to 1.2 K was constructed. Measurements of the current-voltage characteristics (I-V's) were performed on 2H-NbSe2 and a high-T

c
superconductor Y-Ba-Cu-O. Spatial variations in the local density of states (LDOS) relevant to the low temperature phases, CDW and superconductivity, were extracted from data statistics.
The Low Field Hall Coefficient of Copper and Palladium
Authors: Sakamoto Isao , Yonemitsu Kiyoshi
Published: March 2014

Precise measurements of the low field Hall coefficient RH of pure copper and palladium have been made between 2K and 16 K by the use of SQUID. Residual resistance ratios of the Cu and Pd samples were about 22000 and 1500 respectively. We have deduced the temperature dependence of the relaxation times from the RH and the electrical resistivity data using a two group model. For Cu the relaxation times τ of the neck (N) and the belly (B) regions of the Fermi surface vary as 1/τN∼T
3.3 and 1/τB∼T5 and for Pd 1/τh∼T1.9 and 1/τe∼T3, where τh and τe are the relaxation times Γ of the Γ centered electron and the open hole sheets respectively. These results are discussed in terms of the anisotropy of electron-phonon and electron-electron scattering.
Indications of a High Mobility Surface Layer on Oxidized Copper and Aluminum Surfaces at Low Temperatures
Authors: Rzchowski M. S. , Rigby K. W. , Fairbank W. M.
Published: March 2014

We discuss progress in the comparison of the temperature dependence of the microwave surface impedance and of the spatial variations in the surface potential on oxidized copper and aluminum. These measurements test the hypothesis that sharp increases in the microwave surface conductivity of copper and aluminum are caused by the appearance of a high mobility surface layer at low temperatures. An in-situ evaporator in our UHV surface potential apparatus will allow work function measurements of well-characterized surfaces, but the samples must be transferred in air to the surface impedance experiment.
Phonon Scattering by V2+ Ions in GaAs–Evidence of a Low-Spin System
Authors: Butler W. , Challis L J. , Sahraoui-Tahar M. , Salce B. , Ulrici W.
Published: March 2014

Phonon scattering by 3d impurities in GaAs, GaP and InP has been investigated by measuring the low temperature thermal resistance. Seven of the systems studied conform to the expectation that orbital triplets should scatter more strongly than doublets. The weak scattering observed in GaAs:V arises because this ion has a doublet ground state (low spin case) rather than the expected triplet (Hund's rule). This very exceptional case was recently predicted by Katayama-Yoshida and Zunger.
Solubility of 4He in Liquid 3He at Very Low Temperatures
Authors: Nakamura Masaki , Fujii Yoshiko , Shigematsu Toshinobu , Shigi Toyoichiro
Published: March 2014

The phase separation curve of dilute solution of 4He in liquid 3He has been studied using a sensitive dielectric technique and a film-flow-tight valve attached to a cell. The solubility of 4He at low temperatures was larger than the value expected from the equation proposed by Saam et al.
Hole Localization and Interaction in 2-D Heavily Doped p-Type Germanium
Authors: Tessler Leandro R. , Deutscher Guy
Published: March 2014

We have measured conductivity and magnetoconductivity as a function of temperature and magnetic field (T from 1.3 to 4.2 K, H from 0 to 1.25 T) on two-dimensional heavily doped p-type germanium thin films,. The films were semicontinuous, aluminum doped with carrier concentrations up to around 1020 holes/cm and sheet resistances from 350 to 1200 ohm/square at 4.2 K. The resistance depends on temperature as a In T in the range studied, with a between 0.81 and 1.50 e2/2π2\hbar. The magnetoconductivity at low fields and low temperatures is mainly due to localization, positive in the most heavily doped samples and negative in the others. At fields higher than approximately 0.4 T interaction effects become dominant and the magnetoconductivity is negative.
Low Temperature Resistivity Anomalies in Concentrated LiMg Alloys
Authors: Zhao J. , Bass J. , Jr. W. P. Pratt , Sato H. , Schroeder P. A.
Published: March 2014

Previous measurements showing a resistivity anomaly in KRb and dilute KNa and LiMg alloys have been extended to more concentrated LiMg alloys. The anomaly is found to approach the electron-electron interaction limit when the residual resistivity ρo becomes greater than about 100 nΩm. In the most concentrated alloys, the anomalies show large variations when the sample heat treatment is changed. This behavior suggests that microscopic differences within these alloys affect the data.
Phase Coherence, Nonlocal Conductivity and A-B Effect in Normal Metals
Authors: Ebisawa Hiromichi , Isawa Yoshimasa , Maekawa Sadamichi
Published: March 2014

The validity of the basic formula for the voltage fluctuation in network systems, expressed in terms of the quantum correction of the non-local couductivity, is discussed. The characteristic features of the Aharonov-Bohm oscillation in such a system with a ring, where no transport current flows, are presented.
Evidence for an Energy Barrier Impeding the Creation of Quantized Vortices in He II
Authors: Hendry P. C. , Lawson N. S. , Williams C. D. H. , McClintock P. V. E. , Bowley R. M.
Published: March 2014

The rate ν at which negative ions create quantized vortex rings in isotopically pure He II has been measured for temperatures 70<T<500mK, pressures 12<P<19 bar and electric fields 104<E<105Vm-1. The result can be taken to imply the existence of an energy barrier impeding the nucleation process of ∼3K.
Internal Friction and Velocity Measurements at Audio-Frequencies in Neutron-Irradiated Quartz
Authors: Vanelstraete A. , Laermans C. , Leuven K. U. , Lejarraga L. , Schickfus M. von , Hunklinger S.
Published: March 2014

The internal friction and the change of the sound velocity of two neutron-irradiated quartz samples was measured at about 1 kHz as a function of the temperature. The behaviour of both the internal friction and the velocity can be explained in the framework of the tunnelling model. The observations demonstrate the validity of the distribution of relaxation times of the TS proposed by the tunnelling model in the region of long relaxation times: 2×10-7≦τ-1/τm
-1≦5×10-3.
Specific Heat of Amorphous Ge1-xAux near the Metal-Insulator Transition
Authors: Möller T. , Hofacker M. , Löhneysen H. v.
Published: March 2014

In-situ specific-heat measurements between 0.3 K and 2 K of quench-condensed amorphous Ge1-xAux films for x = 0.18 and x = 0.14 are reported. These concentrations are close to xc=0.12 for the metal-insulator transition. The samples exhibit bulk superconductivity at 1.6 and 0.6 K respectively, as determined from the discontinuity in the specific heat. The observed strong decrease of the normal-state electronic specific-heat coefficient from x = 0.18 to 0.14 gives evidence that the density of states at the Fermi energy vanishes upon approaching xc, as previously inferred from tunneling measurements.
The Hall Effect in 2D Electrons on Liquid Helium
Authors: Lea M. J. , Stone A. O. , Fozooni P.
Published: March 2014

The Hall effect has been observed in a two-dimensional sheet of free electrons on the surface of liquid helium at a temperature of 1.4 K and at frequencies of up to 35 kHz. We also observe the transition to a resonant mode at a magnetic field B
o∝1/f.
Quantum Magnetoconductance of the Two-Dimensional Electron Gas on a Liquid Helium Surface
Authors: Sanden M. C. M. van de , Heijden R. W. van der , Waele A. Th. A. M. de , Gijsman H. M.
Published: March 2014

The longitudinal conductivity σxx of the two-dimensional electron system on a liquid helium surface was measured as function of magnetic field for fields up to 4 Tesla. The temperature was in the range 1.4 < T < 2.0 K, so that scattering of electrons by vapour atoms is dominant. When the quantum limit is reached, which means that the Landau level separation \hbarωc is larger than the thermal energy kbT (\hbarωc/kbT≤4 under the present conditions), a deviation from the classical relation σxx∼1/B2 is observed. A discussion is given based on a quantum transport theory.