bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of magnetocaloric effect: Stoner approximation vs DMFT
Authors: Igoshev P A , Nekrasov I A , Pavlov N S , Chinyaev T H , Yakupov E O 
Published: November 2019

AbstractA comparative study of the magnetocaloric effect (MCE) in metals within the single-band Hubbard model on the face-centered cubic (fcc) lattice using both mean-field (Stoner) approximation (MFA) and dynamical mean-field theory (DMFT) is done. The MCE is investigated in the case of second order magnetic phase transition from ferromagnet to paramagnet. To ensure presence of itinerant ferromagnetism in the Hubbard model the special case of spectrum parameters generating giant van Hove singularity at the bottom of the band is considered, while the Fermi levelEfis in the vinicity of the band bottom. To compare MCE within MFA and DMFT temperature dependence of magnetization, total energy and finally entropy for a set of Coulomb interactionsUat zero and finite values of magnetic fieldhfor both methods were performed. Also one of the MCE potentials, isothermal entropy change, as a function of temperature ∆S(T)for both MFA and DMFT is calculated. In the MFA, the expected maximum value of ∆S(T)at the Curie temperatureTC(∆Smax) quite significantly decreases whileUgrows. Similar but much weaker decreasing of ∆Smaxis found for DMFT results. The account of local quantum fluctuations results in larger values of ∆Smaxwithin DMFT than within MFA. A peak width of ∆S(T)at half height is approximately the same for both methods. Another effect of DMFT local quantum fluctuations is the destruction of anomalous Curie temperatureTCdependence onUpresent in MFA, which is invoked by an effect of giant van Hove singularity. However the relative cooling power (RCP) is very close in DMFT and MFA for the same model parameters and goes down uponUincrease.
Ab initio study of DyFe4Ge2 alloy
Authors: Matyunina M V , Zagrebin M A , Sokolovskiy V V , Buchelnikov V D 
Published: November 2019

Abstract
Using density functional theory, the magnetic and electronic properties for DyFe4Ge2 alloy with four different structures were studied. The exchange-correlation effects were treated by the two approximations: local density approximation (LDA) and LDA+U. It is shown, that for all considered structures both approximations give rise to similar results for magnetic moments and partial densities of states for Fe (Ge) atoms. The DOS calculations for Dy atoms demonstrated significant difference between LDA and LDA+U results. The strongest antiferromagnetic and ferromagnetic interactions were found for iron atoms located on regular sublattices in orthorhombic structures.
Magnetocaloric effect in the 2D dilute Ising system
Authors: Shadrin A V , Ulitko V A , Panov Y D 
Published: November 2019

Abstract
We consider the magnetocaloric effect (MCE) for the 2D Ising system with a fixed concentration of non-magnetic mobile charged impurities. Pseudospin formalism and highperformance Monte Carlo simulations are used to describe the system and, in particular, to obtain the temperature dependences of the MCE parameters for our system. The effect of the impurityimpurity interaction strength on the concentration dependence of the MCE parameters is discussed, as well as the possibility of using the MCE effect to reveal a hidden frustration in the system.
Structural, magnetic and magnetocaloric properties of NdPrFe14B and its hydrides
Authors: Tereshina I , Kaminskaya T , Ivanov L , Politova G , Drulis H , Gorbunov D , Paukov M , Tereshina-Chitrova E , Andreev A 
Published: November 2019

Abstract
A systematic study of the influence of interstitial hydrogen on the structure, morphology of surface, magnetic and magnetothermal properties in multicomponent (Nd0.5Pr0.5)2Fe14BHx (x = 0; 2.7; 4.3) are reported. Partial substitution of Pr for Nd allows a decrease of the spin-reorientation transition temperature from 135 K for Nd2Fe14B to 73 K for (Nd0.5Pr0.5)2Fe14B. Hydrides (Nd0.5Pr0.5)2Fe14BHx crystallize in a tetragonal crystal structure (space group P42/mnm) of the Nd2Fe14B-type. Both lattice constants and unit cell volume increase upon hydrogen absorption. It was also found that the surface of the hydrogenated sample was very severely damaged by the introduction of hydrogen. Magnetic studies of both initial compound and the hydrides were performed on bulk and powder samples in static and pulsed magnetic fields up to 14 and 58 T, respectively. Hydrogenation has a significant effect on magnetic properties of a multicomponent alloy (Nd0.5Pr0.5)2Fe14B: Curie temperature and saturation magnetization increase, while temperature of SRT decreases (TSRT = 63 K for (Nd0.5Pr0.5)2Fe14BHx with x = 2.7 and 4.3). The magnetocaloric effect (MCE) in the range of spin-reorientation transition also decreases significantly. We analyzed magnetic properties of (Nd0.5Pr0.5)2Fe14BHx and compare them with that of Nd2Fe14BHx. Magnetic phase diagrams are constructed.
Low-temperature magnetostriction and distortions in the rare-earth Laves phases
Authors: Politova G , Ganin M , Kaminskaya T , Mikhailova A , Nacke B , Filimonov A , Burkhanov G 
Published: November 2019

Abstract
The effects of partial substitution of dysprosium in Tb0.2Dy0.8Co2 by terbium and gadolinium on the structure and magnetic properties have been studied. Two compositions, Tb0.3Dy0.7Co2 and Tb0.2Dy0.7Gd0.1Co2 have been synthesized. Their crystal structure, in contrast to the structure of the original compound, has both tetragonal distortions and rhombohedral distortions at lower temperatures. Anomalies of magnetostriction and magnetocaloric effect near the observed magnetic phase transitions have been studied. The sign-alternating temperature dependences of the longitudinal and transverse magnetostrictions associated with various types of crystal structure distortions of the alloys are revealed.
Effect of lattice vibrations on magnetic properties of metals at finite temperatures
Authors: Melnikov N B , Paradezhenko G V , Reser B I 
Published: November 2019

AbstractWe investigate the effect of electron-phonon interaction in the dynamic spin-fluctuation theory of metallic magnetism. Electron-phonon interaction is represented by fluctuations of the crystal lattice potential. We illustrate the theoretical results in the example of Fe and Ni. We show that the effect of phonons on temperature dependence of magnetic characteristics is appreciable in Fe, but not as large as in the static single-site spin-fluctuation theory and spin dynamics using classical Hamiltonians. On the contrary, in Ni the effect of phonons is small in agreement with the results of the spin dynamics.
Hybrid states of Tamm plasmon polaritons in nanostructures with Bi-substituted iron garnets
Authors: Mikhailova T V , Lyashko S D , Tomilin S V , Shaposhnikov A N , Karavainikov A V , Berzhansky V N 
Published: November 2019

Abstract
The work presents the results of investigation of hybrid states of Tamm plasmon polaritons (TPP) in magnetoplasmonic nanostructures (MPNS) based on Bi-substituted iron garnet (Bi:IG) and Au layers and nanoparticles. To study the interaction of resonances, two MPNS were synthesized with gold-coated dielectric layer of gradient thickness. It was shown the difference in properties of model MPNS with hybrid state of TPP – Fabry-Perot and a single TPP excitation. It was suggested to use the hybrid state to increase the sensitivity of optical sensors.
Magnetization reversal in NiFe2O4/SrTiO3 nanoheterostructures grown by laser molecular beam epitaxy
Authors: Krichevtsov B , Gastev S , Mashkov K , Kaveev A , Korovin A , Lutsev L , Suturin S , Lobov I , Telegin A , Lomov A , Sokolov N 
Published: November 2019

Abstract
NiFe2O4/SrTiO3(001) nanoheterostructures have been fabricated by laser molecular beam epitaxy method. Surface morphology and crystal structure of Ni-ferrite films were analysed by atomic force microscopy (AFM), reflection of high energy electron diffraction (RHEED), X-ray diffraction (XRD). X-ray methods prove the presence of inverse spinel crystal structure of films that was confirmed by measurements of spectral dependence of optical polar Kerr (PMOKE) effect. Study of magnetization reversal for different orientations of magnetic field carried out by vibration sample magnetometry (VSM) and longitudinal magneto-optical Kerr effect (LMOKE) are presented. In-plane magnetization loops exhibit 90° period indicating presence of biaxial magnetic anisotropy. Asymmetry of LMOKE hysteresis loops is related to manifestation of quadratic in magnetization effects in reflection of light.
Strain-magneto-optics in ferrite-spinel – new magneto-optical phenomena associated with magnetoelastic interactions
Authors: Telegin A V , Sukhorukov Yu P , Bebenin N G 
Published: November 2019

Abstract
The correlation between magnetoreflection, magnetotransmission of unpolarized light in the infrared range and the magnetoelastic properties of magnetics is reported for the ferrimagnetic spinel CoFe2O4 single crystal. The new physical mechanism responsible for the spectral and field-dependent peculiarities of magnetoreflection and magnetotransmission in the ferrite-spinel possessing strong magnetostriction is discussed. The influence of a magnetic field on specular reflection and transmission spectrum is likely to be indirect: magnetic-field-induced strong strains and deformations of the crystal lattice lead to the change in the electron energy structure and, hence, optical properties of CoFe2O4. The revealed mechanism of new infrared magnetooptical effect in magnetostrictive magnetics paves the way towards new research area called as a strain-magneto-optics.
Strong changes in electronic transport and magnetic properties of Co2YSi Heusler alloys at Y-component variation
Authors: Perevozchikova Yu A , Semiannikova A A , Terentev P B , Eisterer M , Korenistov P S , Marchenkov V V 
Published: November 2019

Abstract
The Co2
YSi (Y = Ti, V, Cr, Mn, Fe, Co, Ni) Heusler alloys can manifest the properties of half-metallic ferromagnets. These compounds are promising materials for spintronics since almost 100 % spin polarization of charge carriers can be realized at room temperature. We measured the electroresistivity, magnetic and galvanomagnetic properties of the Co2
YSi (Y = Ti, V, Cr, Mn, Fe, Co, Ni) Heusler alloys from 4.2 K to 300 K and in magnetic fields up to 100 kOe. The type, concentration and mobility of charge carriers were estimated. The Y-component variation in the Co2
YSi Heusler alloys is found to affect strongly the number of current carriers and alter the electronic band structure near the Fermi level E
F and, consequently, the electronic transport and magnetic properties of the Co2
YSi (Y = Ti, V, Cr, Mn, Fe, Co, Ni) Heusler alloys.
Simulation of magneto-optical properties of nanocomposites (CoFeZr)x(Al2O3)1-x
Authors: Yurasov A , Yashin M , Ganshina E , Granovsky A , Garshin V , Semenova D , Mirzokulov Kh 
Published: November 2019

Abstract
The magnetooptical spectra of the transverse Kerr effect of (CoFeZr)x(Al2O3)1-x nanocomposites are calculated within the framework of the symmetrized Maxwell-Garnett (SMG) approximation. The quasi-classical size effect and the size distribution of the granules were taken into account. The calculation results for the spectral range 0.5-3.5 eV and different concentrations of the magnetic component are in semi-quantitative agreement with the experimental data. A possible reason for the existing discrepancy is the difference between the optical and magneto-optical parameters of ferromagnetic granules from those corresponding for bulk samples.
Influence of solution acidity on growth kinetics, structure and magnetic properties of Co-P films, obtained by chemical deposition
Authors: Chzhan A V , Podorozhnyak S A , Patrin G S , Rudenko R Yu , Onufrienok V V 
Published: November 2019

Abstract
The results of studies of the effect of solution acidity on the growth kinetics, structure and magnetic properties of Co-P films obtained by chemical deposition are presented. It was shown that the growth of Co-P films in the low pH region occurs mainly due to the growth of crystallite sizes, and in the high pH region, due to an increase in the nucleation rate. From the analysis of the chemical equilibrium of redox reactions, taking into account the balance of citrate and hydroxyl complexes of Co, a qualitative explanation of the features of the change in the rate and nature of the deposition of Co atoms from pH is proposed.
Structure and magnetic properties of melt-spun ribbons of Sm(Co,Fe,Cu,Zr)z with high cobalt content
Authors: Khudina E V , Zheleznyi M V , Minkova I O , Rybin P S , Menushenkov V P 
Published: November 2019

Abstract
In this work the investigation of structure and magnetic properties of SmCo7.5Fe3.09Cu0.84Zr0.3 and SmCo7.52Fe3.01Cu0.84Zr0.28 melt-spun ribbons with high cobalt content after different heat treatments was performed. The phase composition and magnetic properties of the samples were determined. Isothermal aging at 600-800 °C with subsequent slow cooling leads to the slight increase in coercivity of the samples. After arc-melting the phase composition of the samples is hexagonal Sm2Co17 and CoFe. After melt-spinning a small amount of the disordered SmCo7 phase is detected. After aging metastable SmCo7 disappears, and the phase structure is basically hexagonal phase Sm2Co17 and CoFe, except a tiny amount of SmCo5 and rhombohedral Sm2Co17 after aging at 800 °C. Magnetic properties of the samples are relatively low because the phases, essential for the high-coercive state in these alloys, do not form during applied heat treatments.
Negative anisotropy in Fe10Ni90 films
Authors: Savin P A , Adanakova O A , Lepalovskij V N , Kudyukov E V , Polozov K V , Vas’kovskiy V O 
Published: November 2019

Abstract
It is shown that in the Fe10Ni90 film the easy magnetization axis can be formed not along the deposition field, as it occurs in the Fe19Ni81 film, but across, that is a “negative anisotropy” effect occurs. A model that qualitatively describes this effect is proposed. Using the Kerr magnetometer, local measurements of the variation of the direction of the easy magnetization axis over the area of the film sample Fe10Ni90 were carried out and compared with the general view of the domain structure.
Magnetic properties of the GdFeSi – GdTiSi solid solutions
Authors: Kuchin A G , Platonov S P , Gaviko V S , Yakovleva M Yu 
Published: November 2019

Abstract
The GdFe1-x
Ti
x
Si, x=0-0.2 intermetallic compounds with a tetragonal crystal structure of the CeFeSi (P4/nmm)-type have been studied. It was obtained that the lattice parameter c and the Curie temperature increase quickly, whereas the lattice parameter a is almost unchanged in the system with increasing of Ti content. The GdFeSi compound is easily magnetized along the [001] axis, the field of magnetic anisotropy equals to ~3.8 kOe at T = 90 K. The saturation magnetization does not change in the GdFe1-x
Ti
x
Si system.
Magnetic properties of Sr2Ni1-xMgxMoO6 (x = 0.25 and 0.5) double perovskite structure
Authors: Urusova N V , Semkin M A , Filonova E A , Kratochvilova M , Neznakhin D S , Park J-G , Pirogov A N 
Published: November 2019

Abstract
Sr2Ni1-xMgxMoO6 (x = 0.25 and 0.5) double perovskites were synthesized by pyrolysis of glycerol–salt mixtures and their magnetic properties were investigated. X-ray diffraction was employed to refine crystal structures of these perovskite materials and set sample purity degree. The magnetic ground state of Sr2Ni1-xMgxMoO6 (x = 0.25 and 0.5) has been characterized using magnetic susceptibility measurements. They indicate that Sr2Ni0.75Mg0.25MoO6 is ordered in an antiferromagnetic state below 56 K while Sr2Ni0.5Mg0.5MoO6 is paramagnetic.
Features of the scattering of exchange spin waves by layer and superlattice of biaxial ferromagnets
Authors: Poimanov V D , Shavrov V G 
Published: November 2019

Abstract
The paper studies the scattering of exchange spin waves at the interface of biaxial magnetic materials with a uniform ground state and describes a method for finding the reflection and transmission coefficients from an isolated boundary, layer, and multilayer structure of such materials. The breaking of the axial symmetry of the precession of magnetization leads to the formation of surface exchange waves at the interface. These waves correspond to the imaginary roots of the characteristic equation and have the opposite to the bulk waves chirality of precession. Taking them into account aligns the number of boundary conditions and unknown amplitudes. The scattering coefficients are obtained by expanding over a small ellipticity parameter in the zero and first approximations. A comparison with the exact solution was made. It is shown that the frequency dependence of the reflection coefficient can be non-monotonic, and it can turn to zero, which corresponds to the equality of the wave impedances of the adjacent media.
63,65Cu NMR study of the antiferromagnet CuCrO2
Authors: Smolnikov A , Arapova I , Ogloblichev V , Piskunov Y , Sadykov A , Mikhalev K , Furukawa Y , Barilo S , Shiryaev S 
Published: November 2019

Abstract
The 63,65Cu NMR and NQR spectra have been obtained in single crystal sample of CuCrO2 in the magnetically ordered phase. The components of the electric field gradient tensor (EFG) characterizing the structure of the nearest environment of copper ions are determined from the analysis of the spectra. Comparative analysis obtained data with similar data of paramagnetic phase showed that the local charge environment of copper nuclei does not change during the magnetic phase transition.
Precession frequency and switching time of the magnetization vector of the spin-valve free layer with longitudinal anisotropy
Authors: Iusipova Iuliia A 
Published: November 2019

Abstract
In this paper, a magnetization vector dynamics of a spin-valve free layer with the planar anisotropy based on various materials was simulated. Two dynamics types were identified, being of practical interest for MRAM (switching) and STNO (stable precession). The range of current and field values, corresponding to these spin-valve operation modes, were obtained. The numerical calculations of the switching time shown that Co80Gd20 is the best material for a spin valve as a part of MRAM. As a result of calculating the precession frequency, it was concluded that the most suitable for fabrication of STNO ferromagnetic layers is the alloy Fe60Co20B20.
Self-organization in the unit sell of a single crystal spinel Li0.5Ga2.5O4 and self-distribution of magnetic ions of chromium Cr3+
Authors: Shapovalov Vladimir A , Shavrov Vladimir G , Koledov Victor V , Kamantsev Alexander P 
Published: November 2019

Abstract
Self-organization of twelve structurally and magnetically non-equivalent sites and self-distribution of magnetic ions of chromium over these sites at the minima of the crystal field potential in a unit cell of single crystal lithium-gallium spinel Li0.5Ga2.5O4 is considered. The form of the crystal field potential at the location of a magnetic ion is determined by the nearest neighbours. If the crystal symmetry is similar to the cubic one, structurally non-equivalent ion positions are formed. In this case, the compound contains the related number of magnetically non-equivalent positions of the magnetic ion that are found in the electron paramagnetic resonance spectra.
Calculation of the exchange integrals for Co1-xNix alloy by Korring-Kohn-Rostoker method
Authors: Budko Sergey N. , Mamonova Marina V. 
Published: November 2019

Abstract
In this work we investigate the cobalt-nickel alloy magnetic properties. Calculations of lattice constants for Co, Ni and Co1-x
Ni
x
alloy with different concentrations were performed with the VASP framework. Calculations of the exchange integrals were carried out using the SPR-KKR package (spin-polarized relativistic Korring-Kohn-Rostoker method). For pure ferromagnets, the Co exchange interaction is ferromagnetic. For Ni, the exchange interaction of the nearest neighbors also is ferromagnetic, but the exchange interaction of the next nearest neighbors has a very weak antiferromagnetic character. In the Co1-x
Ni
x
alloy, the exchange interaction of the nearest neighbors J

Ni–Co

1 and J

Co–Co

1 increases with increasing nickel concentration. The next nearest neighbors exchange interaction at a concentration of Ni x ≥ 0.5 has an antiferromagnetic character.
Local magnetic study for cluster-layered Fe/Cr nanostructures
Authors: Miyanaga T , Ikeda Y , Hasunuma Y , Ponomarev D , Grebennikov V , Babanov Y A 
Published: November 2019

Abstract
Local magnetic structures of cluster-layered Fe/Cr thin films are studied by X-ray magnetic circular dichroism (XMCD) and extended X-ray absorption fine structure (EXAFS). The magnetic moment of Fe atoms evaluated from XMCD for Al2O3/Cr(70Å)/[Fe(1.2Å )/Cr(10.5Å)]30/Cr(12Å), which shows the minimum point in the resistivity, decreases as the temperature increases and disappears around the temperature of the minimum resistivity. EXAFS shows the local structure of this film around Fe atoms is rather disordered and it can be related the fluctuation of magnetic structure estimated from the theoretical analysis of the temperature dependence of magnetic moments.
Macroscopic quantum coherent effects induced by electric current in dynamics of lanthanide based single molecule toroics
Authors: Plokhov D I , Zvezdin A K 
Published: November 2019

Abstract
The dynamics of a quantum system with a large toroidal moment under the influence of a time-dependent electric current coupled with the toroidal moment is considered. The possibility of observing the quasi-anyonic excitations, the Bloch type oscillations in the precession motion of the toroidal moment, the Stark-type resonances, and the tunnel transitions between different precession modes are discussed.
Magnetic ordering in Fe/X/Gd (X=Cr, Pd) superlattices
Authors: Makarova M , Antropov N , Kravtsov E , Proglyado V , Khaydukov Y , Ustinov V 
Published: November 2019

Abstract
We have studied the influence Cr and Pd spacers on structure and magnetic ordering in Fe/Gd superlattices. The insertion of Cr and Pd spacers in Fe/Gd has been found to cause structural changes in Gd layers. In particular, an additional fcc Gd phase appears in Fe/Cr/Gd along with the main hcp Gd phase, while there is amorphous Gd structure in Fe/Pd/Gd. By combining SQUID magnetometry and polarized neutron reflectometry we have shown that interlayer Fe-Gd exchange coupling through Pd spacers is much stronger than through Cr one.
Influence of diffuse interfaces on the magnetoresistance in trilayer magnetic structures
Authors: Mamonova Marina V. , Prudnikov Vladimir V. , Prudnikov Pavel V. , Samoshilova Anna A. 
Published: November 2019

Abstract
The numerical Monte Carlo study of influence of diffuse interfaces on the magnetoresistance in trilayer magnetic structures Co/Cu(100)/Co and Pt/Co/Cu(100)/Co/Pt is carried out. The calculations of temperature dependence of the CPP magnetoresistance are realized for structures with thickness of cobalt films N=11 monolayers for cases with sharp and diffuse interfaces. Comparison of results shows that diffuse interfaces lead to appreciable influence on the magnetoresistance in these nanostructures.
Microstructure and magnetoresistance of Co90Fe10/Cu and Co65Fe26Ni9/Cu multilayers
Authors: Milyaev M A , Naumova L I , Bannikova N S , Proglyado V V , Patrakov E I , Krinitsina T P , Ustinov V V 
Published: November 2019

Abstract
Investigations of the microstructure, magnetic and magnetotransport properties of the optimized [Co90Fe10/Cu]
n
and [Co65Fe26Ni9/Cu]
n
multilayers with n = 32 prepared by magnetron sputtering are performed. These nanostructures exhibit the magnetoresistance values 83 % and 36 % at room temperature, respectively. The article presents the results of the influence of Co65Fe26Ni9 alloy on the magnetoresistance values and crystal structure of multilayers. In the periodic part of the nanostructure [Co65Fe26Ni9/Cu]
n
based on CoFeNi ternary alloy, besides fcc the formation of a bcc phase in the continuous boundaries around crystallites is found.