Magnetoresistance and Quantum Oscillations in WTe2 Semimetal

Physics of the Solid State - The discovery of extreme magnetoresistance (MR) in nonmagnetic materials attracted attention to WTe2 semimetal. We studied MR in a single crystal of tungsten...     

Low-Temperature Heat Capacity and Phonon Kinetics in Some Rare-Earth Pentaphosphate Single Crystals and Glasses

Journal of Experimental and Theoretical Physics - The influence of the Schottky low-energy excitations related to the presence of rare-earth metals on the thermodynamic and kinetic characteristics...     

Size Effect in Nanocomposites Based on Molecular Ferroelectric Diisopropylammonium Bromide

Physics of the Solid State - We present the results of studies of the dielectric properties of nanocomposites based on Al2O3 oxide films with a pore size of 330 and 60 nm with particles of an...     

Acoustic and NMR investigations of melting and crystallization of indium–gallium alloys in pores of synthetic opal matrices

The paper presents the results of studying the crystallization and melting processes of Ga–In eutectic alloys, which are embedded in opal matrices, using acoustic and NMR methods. The indium concentrations in the alloys were 4, 6, 9, and 15 at %. Measurements were performed upon cooling from room temperature to complete crystallization of the alloys and subsequent heating. It is revealed how the size effects and alloy composition influence the formation of phases with α- and β-Ga structures and on changes in the melting-temperature ranges. A difference was observed between the results obtained using acoustic and NMR methods, which was attributed to different temperature measurement conditions.     

Influence of the fractality of opal matrices on melting and crystallization of decane in pores

In this paper we present the results of studies on melting and crystallization of decane embedded in the pores of opal matrices filled with chemically pure hexadecane. In this studies measured the ultrasonic velocity by the pulse-interference method at frequencies of about 7 MHz in the temperature range 170–290 K.     

Dielectric properties of the nanoporous MCM-41 matrix filled with the (NH4)2SO4 ferroelectric

Variations with temperature of the linear dielectric permittivity and amplitude of the third harmonic were studied for nanoporous MCM-41 matrices with 4.0-nm channel pores filled with the (NH₄)₂SO₄ ferroelectric, in comparison with bulk ammonium sulfate. The measurements were performed upon heating and cooling in the temperature range from 100 K to room temperature. A noticeable shift to low temperatures (by approximately 25 K) for the ferroelectric phase transition in the MCM-41/(NH₄)₂SO₄ nanocomposite as compared to bulk (NH₄)₂SO₄ was revealed. The temperature hysteresis observed at the phase transition in the nanocomposite was approximately 2 K which is close to that in bulk ammonium sulfate. The significant decrease of the transition temperature in nanostructured ammonium sulfate agrees with the theoretical predictions based on the Landau and Ising models of the size effect on the ferroelectric phase transition in isolated small particles.     

Magnetic properties of porous glass-CuO nanocomposites

The magnetization of the porous glass nanocomposite with CuO nanoparticles embedded in the pores has been studied in the temperature range from 1.8 to 350 K for different pore fillings. It has been shown that the magnetic properties of these nanocomposites depend significantly on pore filling. It has been found that, in the low-temperature range for the nanocomposite with a pore filling of 55% and for pressed CuO, the ZFC and FC susceptibilities diverge, a feature which has been almost absent in the nanocomposite with 21% filling. It has been demonstrated that the kink in the temperature dependence of magnetization, which corresponds to the paramagnetic-multiferroic phase transition, does not shift in the sample with a larger pore filling as compared to that observed in the bulk sample.     

Double peaks on ac magnetization in a superconducting Pb-porous glass nanocomposite

Studies of temperature dependences of ac magnetization were carried out for a superconducting lead-porous glass nanocomposite. Double peaks were found on the imaginary part of ac magnetization which were accompanied with double steps on the real part. The lower-temperature anomalies in ac magnetization differed noticeably when they were obtained upon cooling and warming. The double peaks were treated as two phase transitions in the vortex system: the liquid-solid transition which occurs close to the onset of superconductivity and solid-solid one which is triggered by superconductivity in confined lead islands.     

NMR line shift of gallium in GaAs crystals in the temperature range 160–360 K

The shift in the nuclear magnetic resonance (NMR) line of ⁷¹Ga isotopes in GaAs crystals is investigated in the temperature range 160–360 K. It is observed that the position of the resonance line is temperature-independent. The value of the shift relative to an isolated nucleus is 440 and 420 ppm for the three samples investigated. The roles of various contributions to the NMR line shift are discussed. Fiz. Tverd. Tela (St. Petersburg) 40, 1418–1419 (August 1998)     

Ultrasonic attenuation in a LiIO3 crystal

The temperature dependences of the attenuation of longitudinal acoustic waves along the x axis of a LiIO₃ crystal are studied experimentally by the method of Bragg diffraction of light by ultrasound. The measurements are performed in the temperature range from 215 to 335 K at frequencies of 400–690 MHz. Above 260 K, the attenuation is found to exhibit a frequency-independent growth of a relaxational character, which is used to calculate the enthalpy of the activation of ionic motion in the direction normal to the hexagonal axis. In addition, resonance attenuation peaks are observed; as the frequency increases, the peaks are shifted toward lower temperatures. A phenomenological model is proposed to explain the origin of the resonance absorption.