共查询到20条相似文献,搜索用时 15 毫秒
1.
S. Katayama 《Solid State Communications》1976,19(4):381-383
The contribution of a carrier-soft optical phonon interaction to the electrical resistivity of IV–VI compounds is discussed. The calculated resistivity based on a soft mode theory shows a large increase near the transition temperature Tc. It is foound that the observed increase of resistivity of p-SnTe is reproduced by the carrier-soft TO phonon interaction. 相似文献
2.
The group IVB transition-metal pentachalcogenide, HfTe5, exhibits a peak of the electrical resistivity in the vicinity of 76 K. 相似文献
3.
A. E. Petrova E. D. Bauer V. N. Krasnorussky S. M. Stishov 《Journal of Experimental and Theoretical Physics》2007,104(1):47-50
The results of measuring the electrical resistivity of a MnSi single crystal near the ferromagnetic phase transition at atmospheric and high pressures are reported. In contrast to the previous works, compressed helium is used as a pressure-transferring medium. It is shown that the temperature derivative of the electrical resistivity has the form of sharp maximum on the phase-transition line over the entire its length. Moreover, the observed maxima have a fine structure exhibiting a pronounced shoulder at temperatures slightly higher (by approximately 0.5 K) than the peak temperature, which indicates the existence of nontrivial fluctuations in the paramagnetic phase of MnSi. This feature disappears at a pressure of about 0.35 GPa, which corresponds to the tricritical-point coordinate. 相似文献
4.
Resistance ratios of crystals of 2H-NbSe2 grown with and without iodine were measured over the temperature range 6K–40K. Iodine-free crystals had higher ratios than any NbSe2 previously reported and exhibited an abrupt anomaly at the onset of the charge density wave phase. All crystals displayed a cubic temperature dependence of their resistivities below 18K. 相似文献
5.
An unusual temperature and concentration behavior of the resistivity ρ(T, x) in La0.7Ca0.3Mn1−2x
CuxO3 is observed at slight Cu doping (0≤x≤0.05). Namely, the introduction of copper results in a splitting of the resistivity maximum around the metal-insulator transition
temperature T
0(x) into two differently evolving peaks. Unlike the original Cu-free maximum, which steadily increases with doping, the second
(satellite) peak remains virtually unchanged for x<x
c
, increases for x≥x
c
, and finally disappears at x
m
≃2x
c
, with x
c
≃ 0.03. The observed phenomenon is thought to arise from a competition between substitution-induced strengthening of the potential
barriers (which hinder the charge hopping between neighboring Mn sites) and weakening of the kinetic energy of the carriers.
The data are well fitted by assuming a nonthermal tunneling conductivity theory with randomly distributed hopping sites.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 7, 473–478 (10 October 1999)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
6.
Cobalt (Co) and tantalum (Ta) co-substituted BiFeO3 polycrystalline ceramics were prepared by a solid-state reaction and their magnetic and dielectric properties were investigated. Magnetic hysteresis loops were clearly observed in co-substituted specimens and magnetization was greatly improved. The co-substitution decreased the electrical conductivity by six orders of magnitude along with the reduction of grain size. The magnetoelectric coupling was estimated in co-substituted BiFeO3 by determining the changes of the dielectric constant with an external magnetic field. 相似文献
7.
The anomalous behaviour of resistivity in bulk polycrystalline FeMnAl alloys is presented. The minimum in the ?(T) curve at low temperature is due to the Kondo-like behaviour induced by sufficient Al. The minimum at high temperature is due to the magnetic phase transition, that is, from paramagnetism to antiferromagnetism of gap type. 相似文献
8.
9.
M. Kasaya 《Physics letters. A》1976,55(6):365-367
Resistivity measurements on the LixMn1?xSe system revealed that an anomalous dependence of resistivity on Li content occurs between x=0.031 and 0.053 in the impurity conduction region; the resistivity for x=0.053 is 3 × 103 times as large as that for x=0.031. 相似文献
10.
Magnetization at 0.3 and 140 Hz (0–10 Oe) and magnetic relaxation measurements were carried out in detail in the temperature range between 4.2 and 300 K for a polycrystalline Fe65Ni35 alloy. The typical temperature Tg and the magnetic field Hg which correspond to the anomalous temperature in χ-T curves and inflection field in σ-H curves, respectively, are summarized and a H-T diagram is obtained. A strong magnetic relaxation is observed along the Hg-T line. The temperature dependence of Hg is discussed by the thermal activation of 180° domain wall which is pinned strongly by the antiferromagnetic-like clusters below Tg. It is find that H
g is a linear function of T
. 相似文献
11.
Magnetization (0–10 Oe) and magnetic relaxation measurements were carried out in the temperature range between 4.2 and 300 K for three picture-frame samples of Fe65Ni35 alloy whose edges were parallel to 100, 110 and 111, respectively. The typical temperature Tg and the magnetic field Hg which correspond to the anomalous temperature in the χ-T curve and inflection field in the σ-H curve, respectively are summarized and H-Tg and Hg-T diagrams are obtained. A strong magnetic relaxation is observed along the Hg-T line. The dependence of Hg on the crystallographic direction and on the temperature are discussed by the thermal activation process of the 180° domain wall which is pinned strongly by the antiferromagnetic clusters below Tg. The anomaly of magnetization of Fe65Ni35 alloy can be interpreted by the macroscopic picture of the coexistence of ferromagnetic and antiferromagnetic-like regions which may be caused by a statistical fluctuation of alloy composition. 相似文献
12.
The thermal conductivity of cold-worked and heat-treated Ti55Nb45 alloys has been measured in the temperature range between 0.6 and 1.5 K. Anomalously strong scattering of phonons for every sample and the remarkable enhancement in the thermal resistivity caused by the annealing at 500°C on cold-worked alloys have been found. These behaviors indicate the existence of an anomalous phonon scattering mechanism besides dislocation scattering in Ti55Nb45 alloys. Electron diffraction patterns show the circular diffuse streaks characteristic of the precursory lattice distortion for the ω atomic configuration. Two kinds of models which correlate the anomalies in the phonon scattering with the lattice instability of the β phase of Ti-Nb matrix are described. 相似文献
13.
O. N. Bakharev A. V. Dooglav A. V. Egorov E. V. Krjukov Yu. A. Sakhratov M. A. Teplov H. B. Brom J. Witteveen 《JETP Letters》1996,64(5):398-403
The nuclear magnetic relaxation of 169Tm in TmBa2Cu3O6+x
(x=0.1–1.0, Δ x=0.1) and TmBa2Cu4O8 is studied at temperatures below 5 K. In all the samples, the Tm spin-lattice relaxation proceeds via intrinsic paramagnetic
centers (PCs) like Cu2+ or copper-oxygen spin-polarized clusters. The experimental data for TmBa2Cu3O6+x
support the idea of the structural (chemical) micro-phase separation in oxygen-deficient 123 compounds. Apparently, the samples
with x⩾0.4 contain hole-poor nonsuperconducting regions, enriched with PCs, and hole-rich (PC-poor) superconducting regions. The
volume fraction f
n of the PC-rich phase reaches a maximum value of 0.85 at x=0.4 and decreases monotonically with increasing x (f
n=0.5, 0.3, and 0.25 at x=0.5, 0.6, and 0.7, respectively). The Tm spin-lattice relaxation in the underdoped TmBa2Cu4O8 compound indicates that this sample, in contrast to oxygen-deficient TmBa2Cu3O6+x
, has a homogeneous composition. However, the Tm spin-spin relaxation measurements reveal two sorts of the Tm nuclear spins
in Tm124, having different NMR spectra and different relaxation times T
2. The latter result is evidence of electronic phase separation in CuO2 phases.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 5, 365–370 (10 September 1996)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
14.
A. Mahesh Kumar M. Chaitanya Varma G.S.V.R.K. ChoudaryP. Prameela K.H. Rao 《Journal of magnetism and magnetic materials》2012,324(1):68-71
The study of gadolinium substitution in small amounts on the saturation magnetization and DC resistivity of nickel-zinc nanoferrite has led to the understanding of the degree of formation of a secondary orthoferrite GdFeO3 phase, the generation of cationic and oxygen vacancies and the dilution of gadolinium in the lattice. The role of secondary phase in modifying the electromagnetic properties has been stressed by making further investigations on the Curie temperature and the activation energies. 相似文献
15.
N. B. Bakulina M. I. Kurkin S. A. Gudin A. V. Gapontsev 《Physics of the Solid State》2010,52(2):328-334
The possibility of appearing jumps in the magnetization curves of Fe/Cr multilayers has been predicted under the assumption
that magnetic ordering in chromium interlayers has the form of a linearly polarized spin-density wave. This possibility has
been analyz ed for an Fe/Cr/Fe three4ayer film with a conventional quality of Fe/Cr interfaces, which does not ensure a change
in the ferromagnetic and antiferromagnetic orientations of the magnetizations of neighboring iron layers with a variation
in the thickness of the chromium interlayer by one atomic layer (short oscillation period). The model used suggests that the
wave vector of the spin-density wave is responsible for the experime ntally observed long period of these oscillations. Relationships
have been derived for the range of thicknesses of chromium interlayers in which the appearance of the predicted effect can
be expected, and the magnitude of the effect has been evaluated. 相似文献
16.
Cubic ZnMnO3 powder in the form of well-crystalline nanoflakes have been synthesized at low temperatures from a nitrate precursor. The electrical properties of cubic ZnMnO3 samples have been established by DC resistivity (ρ) and thermo-electric power (Seebeck coefficient) measurements on a pressed pellet. The material exhibits insulator behavior with 0.7 eV acceptor ionization energy in the measured temperature range of 170-300 K. The thermo-electric power indicates a positive sign of the charge carriers. The obtained material exhibits a superparamagnetic signature with a blocking temperature of 9 K and the ZFC-FC splitting temperature of 15 K. 相似文献
17.
A randomly inhomogeneous composite consisting of two, ferromagnetic and nonmagnetic (para-or diamagnetic), phases is considered.
The dependence of the effective permeability of the composite on the concentration of the ferromagnetic phase and on the applied
magnetic field is found for the case of the negligible hysteresis loop. When the hysteresis loop is appreciable, the remanent
magnetization as a function of the ferromagnet concentration is calculated. 相似文献
18.
Wanju Luo Shuxia Zhang Dongliang Wang Yanwei Ma Fangwei Wang Kazuo Watanabe 《Journal of magnetism and magnetic materials》2012
The effect of magnetic annealing treatment on the magnetization of multiferroic BiFeO3 was studied systematically. A series of pelletized nano-sized BiFeO3 powders were annealed at high temperature under different magnetic fields. Typical ferromagnetic hysteresis loops were obtained at room temperature of the ceramics which were derived from ferromagnetic BiFeO3 precursors. On the other hand, antiferromagnetic behaviors were observed in other samples synthesized from nonmagnetic precursors. The enhanced magnetic properties were ascribed to the magnetic anisotropy which was induced by the strong magnetic fields. This work indicates that the strong magnetic annealing method is an alternative approach to tuning the magnetic properties of high performance multiferroic materials with canted antiferromagnetic ordering. 相似文献
19.