共查询到20条相似文献,搜索用时 15 毫秒
1.
S. S. Aplesnin V. V. Kretinin A. M. Panasevich K. I. Yanushkevich 《Physics of the Solid State》2017,59(4):667-673
The capacitance, inductance, and dissipation factor of the Gd x Bi1–x FeO3 films were measured in the temperature range of 100 K < T < 800 K in magnetic fields of up to 8 kOe at frequencies of 0.1–100 kHz. The magnetic susceptibility maxima in the low-temperature region and dependences of the relaxation time and inductance on prehistory of the films cooled in zero and nonzero magnetic fields are established. The giant increase in magnetic capacitance in the external bias electric field is found. The results obtained are explained by the domain structure transformation in external electric and magnetic fields. 相似文献
2.
The electronic structure and ground state parameters of B2 RuAl-based refractory alloys have been investigated in the framework of the density functional theory using the exact muffin-tin
orbital method in combination with the coherent potential approximation. It has been demonstrated that the number of states
at the Fermi level for the Ru1 − x
Me
x
Al alloys as a function of the alloying metal content has a minimum, which indicates a change in the Fermi surface topology
and the presence of specific features in the behavior of elastic constants. It has been concluded that the electronic structure
of the alloys can be described in terms of the rigid band model. The nonlinear variations of the lattice parameters of the
alloys has been explained. 相似文献
3.
The influence of Gd doping at La-site on the electrical transport properties and the colossal magnetoresistance of La0.7−x
Gd
x
Sr0.3MnO3 (x=0.00, 0.10, 0.15, 0.20, 0.30, 0.40, 0.50, 0.60, and 0.70) is studied. The experimental results indicate that the transport
properties exhibit abnormal behavior under high doping condition. Forx=0.50, we find that a transition from metal to insulator occurs after the occurrence of insulator-metal transition nearT
c, which seldom occurs in ABO3 structure. For samplesx=0.60 and 0.70, it exhibits insulator behavior far aboveT
c. These abnormal behaviors are attributed to different magnetic background, i.e. the system undergoes a transition from long
range ferromagnetic order to the cluster-spin glass state and further to antiferromagnetic order. 相似文献
4.
M. M. Markina K. V. Zakharov A. N. Vasil’ev I. Balasz I. Deac E. Burzo 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(2):190-192
The thermodynamic and magnetic properties of the La1 − x
Pb
x
MnO3 (0.24 ≤ x ≤ 0.40) solid solution system were investigated in the temperature range of 4.2–340 K. All objects were ferromagnetics with
Curie temperature T
C
≈ 320–340 K, which slowly increased with x. The M(T) behavior in the magnetic ordering region indicated a nonuniform ground state, due possibly to the competition of ferromagnetic
and antiferromagnetic interactions. The increase in the saturation magnetic moment with x can be described by a simple model of the binary bonds in La1 − x
Pb
x
MnO3. 相似文献
5.
Mitsuo Kataoka 《Czechoslovak Journal of Physics》1996,46(4):1857-1858
To clarify the origin of the giant magnetoresistance (GMR) observed in La1?x A x MnO3 (A2+=Sr2+, Pb2+, Ba2+ and Ca2+), we have investigated theoretically the electrical resistivity ρ of carriers in the background of Mn spins which interact with each other through the double exchange interaction. It has been found that extraordinarily large pin fluctuations caused by the instability of the ferromagnetic state are responsible for the transport anomalies including the GMR. 相似文献
6.
S. V. Khasbulatov A. A. Pavelko L. A. Shilkina L. A. Reznichenko G. G. Gadjiev A. G. Bakmaev M. -R. M. Magomedov Z. M. Omarov V. A. Aleshin 《Thermophysics and Aeromechanics》2016,23(3):445-450
An extensive study was performed to establish correlations between the crystal structure, the grain composition, and the dielectric and thermophysical properties of high-temperature multiferroics of the Bi1?x Dyx FeO3 type (x = = 0.05–0.20). It is shown that a trade-off between the macroresponses in the materials is achieved at x = 0.10; this circumstance permits recommendation of the materials for practical use. 相似文献
7.
O. A. Savinskaya A. P. Nemudry A. N. Nadeev S. V. Tsybulya N. Z. Lyakhov 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(8):1053-1054
The structure of high-temperature SrFe1 − x
Mo
x
O3 − z
(0 ≤ x ≤ 0.5) phases was studied. Such studies are necessary to understand the mechanism of oxygen transport in membrane materials
used for high-temperature oxygen separation. 相似文献
8.
A generalized expression relating the magnetoresistance of manganites La1 − x
Ag
x
MnO3 with the change in the magnetic entropy has been proposed. The correct inclusion of the acting mechanisms of appearance of
the magnetoresistance is shown to lead to adequate agreement between the experimental and calculated values of ΔS
M
. 相似文献
9.
I. K. Kamilov A. G. Gamzatov A. B. Batdalov A. S. Mankevich I. E. Korsakov 《Physics of the Solid State》2010,52(4):789-793
The magnetocaloric effect and the heat capacity of La1 − x
K
x
MnO3 (x = 0.1, 0.15, 0.175) ceramic samples have been studied at temperatures in the range 77–350 K and in magnetic fields of up
to 27 kOe. The technique for preparing the samples has been described. The heat capacity anomalies related to the ferromagnetic-paramagnetic
magnetic phase transition have been revealed and interpreted. It has been demonstrated that the change in the magnetic entropy
ΔS calculated from the data on the heat capacity C
p
and direct measurements of the magnetocaloric effect ΔT reaches values that are of practical interest. 相似文献
10.
A. V. Bogach G. S. Burkhanov V. V. Glushkov S. V. Demishev O. D. Chistyakov N. E. Sluchanko 《Journal of Experimental and Theoretical Physics》2007,105(1):108-111
The influence of substitution on the binding energy of many-body states and the formation of the magnetically ordered state in a heavy-fermion compound (CeAl2) have been studied by measuring the transport characteristics (Hall effect, resistivity) in intermetallic compounds of the Ce(Al1?x M x )2 system (M = Ni, Co; x ≤ 0.08). It is established that the Hall coefficient R H in Ce(Al1?x Co x )2 intermetallides with x = 0.05 and 0.08 grows by more than an order of magnitude as the temperature decreases from 1.8 to 300 K. The experimental data are used to estimate the effective mass of charge carriers, the relaxation time, and the localization radius of many-body states. 相似文献
11.
Yang Wang Yu Sui Xianjie Wang Wenhui Su 《Applied Physics A: Materials Science & Processing》2011,104(1):135-142
The Seebeck coefficient is a function of carrier concentration and configurational entropy. In this report, we semi-theoretically
investigate the Seebeck coefficient of Ln
x
Ca1−x
MnO3 (Ln=Rare-earth) perovskites based on the electronic structure of the 3d orbitals of Mn ions, using the developed Heikes model, Boltzmann transport model, and diffusion model. The results show that
the Seebeck coefficient of such a strongly correlated electron system in paramagnetic state is remarkably affected by site
degeneracy. As temperature decreases, the evolution of the spin and orbital degrees of freedom together with the change in
phonon scattering mode describes the Seebeck coefficient behavior satisfactorily. The phonon drag effect at low temperature
is also discussed. 相似文献
12.
S. V. Trukhanov M. V. Bushinsky I. O. Troyanchuk H. Szymczak 《Journal of Experimental and Theoretical Physics》2004,99(4):756-765
The structural, magnetic, and electrotransport properties of La1?xSrxMnO3? x/2(0≤x≤0.30) manganites with perovskite structure are investigated experimentally as a function of oxygen deficiency. In the solid solutions La1?xSrxMnO3, a change in the type of symmetry of the unit cell is observed at x=0.125. Samples with x≤0.125 are characterized by an O′-orthorhombic unit cell, whereas samples with x>0.125 are characterized by a rhombohedral unit cell. The structural properties of the anion-deficient solid solutions La1?xSrxMnO3?x/2 are analogous to those of the stoichiometric system. It is assumed that, as the oxygen content decreases, La1? xSrxMnO3?x/2 anion-deficient solid solutions experience a series of successive magnetic phase transformations in the ground state: from an A-type (x=0) antiferromagnet to a cluster spin-glass-type inhomogeneous magnetic state (0.175>x≤0.30) through a two-phase (antiferromagnetic and ferromagnetic) state (0>x≤0.175). The anion-deficient solid solution with x=0.175 has the maximal value of the ferromagnetic component. As the oxygen deficiency increases, the resistivity of La1? xSrxMnO3?x/2 samples first decreases (up to a value of x=0.175), acquiring an activation character, and then increases (up to a value of x=0.30). In this case, none of the anion-deficient solid solutions exhibits a metal-semiconductor transition in the whole range of concentrations considered. A peak of magnetoresistance at a temperature below the point of magnetic ordering is observed only in the sample with x=0.175. The results of experiments carried out with a series of La1?xSrxMnO3?x/2 anion-deficient solid solutions are summarized in the concentration diagrams of the spontaneous magnetic moment and the critical temperature of magnetic phase transitions. Hypothetical magnetic phase states are pointed out. The experimental results obtained can be interpreted in terms of the phase-separation model and the competition between ferromagnetic and antiferromagnetic indirect superex-change interactions. It is assumed that Mn3+-O-Mn3+ indirect superexchange interactions in the orbitally disordered phase are positive in the case of octahedral coordination of manganese ions and are negative when the coordination of at least one Mn3+ ion is pentahedral. 相似文献
13.
The magnetocaloric effect ΔTex and the magnetization in La1?xSrxMnO3 single crystals (x=0.1, 0.125, 0.175, 0.3) have been experimentally studied. The magnetic entropy and the magnetocaloric effect ΔTth were computed from magnetization curves. All the samples exhibited a maximum in the ΔTth(T) curve at T=T max ′ . A step was observed on the ΔTex(T) curve in the region of T max ′ , with the value of ΔTex on this step being substantially smaller than ΔTth. The step on the ΔTex(T) curve was followed by a maximum, which appeared at a temperature 20–40 K above T max ′ . This anomalous behavior of ΔTex and ΔTth is assigned to the coexistence of two magnetic (ferro-and antiferromagnetic) phases in the crystal. The calculated value of ΔTth is determined primarily by the ferromagnetic part of the crystal and disregards the negative contribution from the antiferromagnetic part of the crystal to ΔTex. 相似文献
14.
The barium strontium titanate ceramics Ba1 − x
Sr
x
TiO3 with a spatially variable composition has been prepared according to the thick film technology (tape casting). The strontium
content over the film thickness is varied from 0 to 30 mol %. The structure and polarization characteristics of the samples
prepared have been investigated. It has been found that the polarization characteristics of multilayer structures are determined
by the ratio between the thicknesses of layers with different compositions and by their properties. No shift of the hysteresis
loops in the graded thick Ba1 − x
Sr
x
TiO3 (
x
= 0–0.3) films has been revealed. The results obtained have been analyzed in the framework of modern theoretical approaches. 相似文献
15.
The structures of Y2Fe17−x
Cr
x
are simulated by theab initio potentials. The site preference of Cr atom in Y2Fe17 is evaluated and the order is determined as 4f, 12j, which is close to the experimental result. Based on the site preference
behavior, the calculated parameters and the atom sites of Y-Fe-Cr system are studied. The result corresponds well to observed
data. Further, the DOS of the relaxed structures are calculated and the variation in Curie temperature is explained qualitatively
by the spin-fluctuation theory. 相似文献
16.
The phenomenological theory of phase transition in Pr0.6 Ca0.4 MnO3 manganite is developed. It is shown that this is the orbital phase transition and that the two electronic states of the manganese ion, which are discussed in the literature, result from two different types of condensation of the same orbital order parameter. Thus, the manganese ions in Pr1?xCax MnO3 manganites with 0.3≤x≤0.5 may be in either of the two electronic states, depending on the thermodynamic parameters. 相似文献
17.
S. F. Dubinin V. I. Sokolov A. V. Korolev S. G. Teploukhov Yu. G. Chukalkin V. D. Parkhomenko N. B. Gruzdev 《Physics of the Solid State》2008,50(6):1087-1090
The spin system of a Zn1 ?x Cr x Se bulk crystal (x = 0.045) was studied using thermal-neutron diffraction and magnetic measurements. Previously, it was reported in the literature that thin films (~200 nm thick) of this type of semiconductors exhibit a ferromagnetic order. In this study, the ferromagnetic order is found to be absent in the bulk crystal. 相似文献
18.
A. V. Germanenko G. M. Minkov O. E. Rut A. A. Sherstobitov B. N. Zvonkov 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(2):219-222
The temperature dependence of the conductivity of the two-dimensional hole gas in an asymmetric GaAs/In x Ga1 ? x As/GaAs quantum well has been investigated. It is shown that fast spin relaxation leads to metallic-like behavior of the temperature dependence of the conductivity. 相似文献
19.
The interfaces in complex La2 − x
Sr
x
CoO4 oxides (0.1 < x < 1.5) obtained by the ceramic method were studied in detail. To determine the chemical composition of the interfaces and
their effect on the properties of ceramics, the magnetic and electric properties were investigated and X-ray phase and micro
X-ray analyses were performed. It was found that the mechanical stability of the samples is determined by the presence of
lanthanum in the surface layer. 相似文献
20.
V. V. Ogloblichev A. V. Pogudin Yu. V. Piskunov S. V. Verkhovskii A. Yu. Yakubovsky A. Trokiner 《JETP Letters》2005,82(2):81-85
The Knight shift 207Ks for the 207Pb nuclei in the metal phase of the oxides BaPb1?xBixO3 (x < 0.35) has been analyzed as a function of the concentration. The shift, which is proportional to the density of states near the Fermi energy: 207Ks ~ N(EF), reaches a maximum for an oxide with the maximum superconducting transition temperature Tc(x ≈ 0.25) = 12 K. A significant increase in the width of the shift distribution with the Bi concentration testifies to the formation of a nonuniform state of the electronic system in the conduction band of superconducting oxides, which is accompanied by an increase in short-wavelength contributions to the spin susceptibility. To detect the 207Pb NMR spectra in superconducting oxides with x > 0.2, the 17O-207Pb spin-echo double-resonance method is used, which provides successful detection of the 207Pb NMR signal with an anomalously high rate of spin-spin relaxation T 2 ?1 > 500 ms?1. Thus, fundamental restrictions arising in investigations of rapidly relaxing 207Pb nuclei, which are “unobservable” in superconducting oxides BaPb1?xBixO3 when they are studied by traditional single-resonance methods of pulse NMR spectroscopy, have been overcome. 相似文献