共查询到20条相似文献,搜索用时 46 毫秒
1.
Yu. B. Kudasov A. I. Bykov M. I. Dolotenko N. P. Kolokol’chikov M. P. Monakhov I. M. Markevtsev V. V. Platonov V. D. Selemir O. M. Tatsenko A. V. Filippov A. G. Volkov A. A. Povzner P. V. Bayankin V. G. Guk 《JETP Letters》1998,68(4):350-355
The magnetic susceptibility and conductivity of single-crystal iron monosilicide are investigated in ultrahigh magnetic fields
up to 450 T at a temperature of 77 K. It is found that the conductivity of iron monosilicide increases continuously by two
orders of magnitude as the magnetic field increases. The results obtained can be interpreted as a semiconductor-metal transition
induced by the magnetic field. The dependence of the conductivity on the magnetic field is described well on the basis of
the spin-fluctuation theory.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 4, 326–330 (25 August 1998) 相似文献
2.
N. E. Sluchanko V. V. Glushkov S. V. Demishev M. V. Kondrin K. M. Petukhov A. A. Pronin N. A. Samarin Y. Bruynseraede V. V. Moshchalkov A. A. Menovsky 《JETP Letters》1998,68(10):817-822
The temperature dependence of the Hall coefficient in the interval 1.8–300 K is investigated in detail in high-quality single-crystal
samples of a Kondo insulator — iron monosilicide. It is established that the parameter R
H
(T,H=12.5 kOe) changes sign twice in the temperature interval employed, and at temperatures below T
m
≈7 K an anomalous (magnetic) component appears in the angular and field dependences of the Hall voltage. The results of the
experimental investigations of R
H
(T,H
0
) in FeSi are discussed on the basis of the phase diagram in the model of an excitonic insulator.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 10, 774–778 (25 November 1998) 相似文献
3.
The electrical conductivity, magnetization, and magnetoresistance of manganites La1 − x
Ag
x
MnO3 have been investigated in the temperature range 78–300 K. The samples have been synthesized by the sol-gel method. At room
temperature, the magnetic field of 0.6 T has no effect on the electrical conductivity. As the temperature decreases, an abrupt
jump is observed in the magnetization curve due to the semiconductor-metal phase transition. This transition hardly affects
the temperature dependence of the resistance. 相似文献
4.
N. E. Sluchanko V. V. Glushkov S. V. Demishev M. V. Kondrin V. Yu. Ivanov K. M. Petukhov N. A. Samarin A. A. Menovsky V. V. Moshchalkov 《Journal of Experimental and Theoretical Physics》2001,92(2):312-325
Low-temperature anomalies in the physical properties of iron monosilicide are analyzed based on the results of thorough measurements of the conductivity, Hall coefficients, thermo emf, and magnetic characteristics of high-quality single-crystal FeSi samples at liquid helium (LHe) and intermediate temperatures. It is demonstrated that the most adequate and consistent interpretation of the experimental magnetic, transport, and optical characteristics can be given within the framework of the Hubbard model. The model parameters are determined and the arguments are presented which provide evidence of the spin polaron formation and the density of state (DOS) renormalization taking place in FeSi in the vicinity of the Fermi energy at intermediate temperatures. It was found that a decrease in the sample temperature in the region of T < T c ≈ 15 K is accompanied by a transition to a coherent regime of the spin density fluctuations. As a result, the ferro-magnetic character of the interaction leads to the formation of magnetic microdomains with a characteristic size ~10 Å. The exchange-induced magnetization enhancement in the vicinity of charge carriers in these microdomains probably accounts for the anomalous components in the Hall coefficient and the magnetization hysteresis observed in FeSi at LHe temperatures. The nature of the low-temperature transition at T m ≈ 7 K in the system of interacting magnetic microparticles in iron monosilicide is discussed. 相似文献
5.
N. Guskos J. Typek M. Wabia V. Likodimos H. Fuks I. Rychlowska-Himmel J. Walczak 《Applied magnetic resonance》1998,14(2-3):397-402
The temperature dependence of the EPR spectrum for the α-phase of iron tungstate has been investigated in the temperature range of 40–260 K. At temperatures betweenT 1 ≈ 250 K andT 2 ≈ 205 K where the antiferromagnetic phase transition occurs, a relatively narrow EPR line arising from the dominant iron(III) species has emerged, gaining intensity with the temperature increase. Its linewidth temperature evolution could be described by Huber equation, with TN = 200 K, which is consistent with the peak seen in magnetic susceptibility measurements, while the correspondingg-factor shifts to higher fields reflecting the build-up of internal field emerging from increasing shortrange order in the spin system. At temperatures lower than T2, a very broad and distorted EPR line with temperature dependentg-factor and linewidth has been observed reflecting the corresponding rise of the magnetic susceptibility below the antiferromagnetic phase transition, presumably arising from magnetic clusters embedded in the antiferromagnetic background. 相似文献
6.
A. A. Demidov I. A. Gudim E. V. Eremin 《Journal of Experimental and Theoretical Physics》2012,114(2):259-272
The magnetic properties of ferroborate single crystals with substituted compositions Nd1 − x
Dy
x
Fe3(BO3)4 (x = 0.15, 0.25) with competing exchange Nd-Fe and Dy-Fe interactions are investigated. For each composition, we observed a
spontaneous spin-reorientation transition from the easy-axis to the easy-plane state and step anomalies on the magnetization
curves for the spin-flop transition induced by a magnetic field B | c. The measured parameters and effects are interpreted using a unified theoretical approach based on the molecular field approximation
and on calculations performed in the crystal-field model for the rare-earth ion. The experimental temperature dependences
of the initial magnetic susceptibility from T = 2 K to T = 300 K, anomalies on the magnetization curves for B | c in fields up to 1.8 T, and their evolution with temperature, as well as temperature and field dependences of magnetization
in fields up to 9 T are described. In the interpretation of experimental data, the crystal-field parameters in trigonal symmetry
for the rare-earth subsystem are determined, as well as the parameters of Nd-Fe and Dy-Fe exchange interactions. 相似文献
7.
A. N. Vasil’ev 《JETP Letters》1999,69(11):876-880
An antiferromagnetic transition is observed in the quasi-one-dimensional metal-oxide compound LiCuVO4. A wide peak is observed in the temperature dependence of the magnetic susceptibility at T
M
=28 K, and the magnetic susceptibility exhibits a sharp drop at T
N
≈4 K. As the magnetic field increases, the antiferromagnetic-ordering temperature T
N
=2.3 K at first increases somewhat and then decreases rapidly. The exchange interaction in the chains of copper-oxygen octahedra
is estimated to be J
1=22.5 K. The interchain interaction is estimated to be J
2∼1 K.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 11, 828–831 (10 June 1999) 相似文献
8.
9.
The temperature dependence of electrical conductivity σ (77–300 K) and magnetic susceptibility χ (2–300 K) of AgxTiSe2 in the Ag1/4TiSe2 phase has been studied in order to determine the possibility of preserving the charge-density-wave state in silver-intercalated
TiSe2. The behavior of χ and σ in this phase is compared with that of the starting compound TiSe2.
Fiz. Tverd. Tela (St. Petersburg) 40, 2165–2167 (December 1998) 相似文献
10.
T. V. Drokina G. A. Petrakovskii L. Keller J. Schefer A. D. Balaev A. V. Kartashev D. A. Ivanov 《Journal of Experimental and Theoretical Physics》2011,112(1):121-126
The magnetic structure of the NaFeGe2O6 monoclinic compound has been experimentally investigated using the elastic scattering of neutrons. At a temperature of 1.6
K, an incommensurate magnetic structure has been observed in the form of an antiferromagnetic helix formed by a pairs of the
spins of the Fe3+ ions with helical modulation in the ac plane of the crystal lattice. The wave vector of the magnetic structure has been determined and its temperature behavior
has been studied. The analysis of the temperature dependences of the specific heat and susceptibility, as well as the isotherms
of the field dependence of the magnetization, has revealed the existence of not only the order-disorder magnetic phase transition
at the point T
N = 13 K, but also an additional magnetic phase transition at the point T
c = 11.5 K, which is assumingly an orientation phase transition. 相似文献
11.
V. E. Arkhipov V. E. Startsev V. P. Dyakina J. Klamut Ya. M. Mukovskii A. Czopnik 《JETP Letters》1998,68(1):42-46
Magnetization measurements were performed on a lanthanum manganite La0.9Sr0.1MnO3 single crystal in the temperature interval 4.2–300 K and magnetic field interval 50 Oe-55 kOe in two sample cooling regimes:
1) cooling down to 4.2 K in a high (55 kOe) magnetic field, and 2) cooling in a “zero” field. It is shown that the temperature
dependences of the magnetization M(T) are substantially different in these regimes. Pronounced anomalies of M(T) were observed at temperatures T*=103 K and T
c
=145 K. The first anomaly is attributed to a structural transition, while the second one corresponds to a ferromagnet-paramagnet
phase transition. The magnetization of a La0.9Sr0.1MnO3 single crystal in the cooling regimes studied shows typical “spin-glass” behavior.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 1, 39–43 (10 July 1998) 相似文献
12.
S. A. Nikitin T. I. Ivanova I. G. Makhro Yu. A. Tskhadadze Yu. F. Popov O. D. Chistyakov N. F. Vedernikov 《Physics of the Solid State》1997,39(7):1128-1131
The magnetic properties and crystal structure of GdxLa1−x
CoSi compounds (x=0, 0.25, 0.5, 0.65, 0.8, 1) are investigated. The anisotropy of the magnetic properties are analyzed for a GdCoSi single
crystal. The temperature dependences of the magnetic susceptibility and the tetragonal lattice parameters of GdCoSi are characterized
by anomalies in the vicinity of the magnetic phase transition temperatures, 166 K and 300 K. The Néel temperatures, the effective
magnetic moments, and the paramagnetic Curie temperatures of these compounds decrease as gadolinium is replaced by lanthanum.
The compound LaCoSi is a Pauli paramagnet. The results are discussed on the basis of a model that takes into account the presence
of positive and negative exchange interactions and the itinerant magnetism of the cobalt sublattice.
Fiz. Tverd. Tela (St. Petersburg) 39, 1270–1274 (July 1997) 相似文献
13.
E. V. Shevchenko E. V. Charnaya E. N. Khazanov A. V. Taranov A. S. Bugaev 《Physics of the Solid State》2017,59(4):733-736
The temperature dependence of the ac magnetic susceptibility of a single-crystal mixed rare-earth garnet Er2HoAl5O12 has been investigated within the range from 1.8 to 300 K in a zero constant field and in applied bias fields of up to 9 T. In the absence of a constant magnetic field the magnetic susceptibility followed the Curie–Weiss law. The application of a constant magnetic field caused a magnetic phase transition, the temperature of which increased with increasing magnetic field. The temperature of the maximum of the ac magnetic susceptibility, which is a characteristic of the phase transition, did not show a noticeable dependence on the frequency of the alternating magnetic field. 相似文献
14.
G. I. Harus A. N. Ignatenkov N. K. Lerinman A. I. Ponomarev L. D. Sabirzyanova N. G. Shelushinina N. A. Babushkina L. M. Belova 《JETP Letters》1996,64(6):444-449
The temperature and magnetic-field dependences of the resistivity ρ and Hall effect R(j‖ab, B‖c) in a Nd1.82Ce0.18CuO4−δ
single crystal film (T
c
=6 K) is investigated at temperatures 1.4≤T≤20 K and magnetic fields 0≤B≤5.5 T. At the lowest temperature T=1.4 K the resistive state (exhibiting resistivity and the Hall effect) arises in a magnetic field B=0.5 T. A transition to the normal state is completed at B
c
2≃3 T, where the Hall coefficient becomes nearly constant. The negative magnetoresistance due to the weak-localization effect
in the normal state is observed for B>3 T. The nonmonotonic behavior and the inversion of the sign of R(B) in the mixed state are explained in a reasonable way by the flux-flow model with the effect of pinning taken into account.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 6, 407–411 (25 September 1996)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
15.
L. I. Leonyuk R. Z. Levitin L. A. Ponomarenko V. V. Snegirev A. N. Vasil’ev G. Dhalenne A. Revcolevschi 《JETP Letters》1996,64(3):166-170
The longitudinal and transverse magnetostriction λ of the spin-Peierls compound CuGeO3 in the b-c plane is measured in magnetic fields up to 20 T both above and below the transition temperature T
sp=14.3K. It is found that for a given crystallographic direction the value of magnetostriction is weakly dependent on the magnetic
field direction. In the uniform U phase at T⩾T
sp, λ is negative and approximately equal in the b and c directions, while in the dimerized D phase at T<T
sp, λ is positive and λ
b
>λ
c
. At low temperatures, λ increases sharply at the magnetic-field-induced transition from the dimerized to the magnetic M phase. The experimental data allow estimation of the stress derivatives of the antiferromagnetic intrachain exchange interaction
parameter and of the stress dependence of the critical field of the D-Mphase transition.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 3, 156–159 (10 August 1996)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
16.
V. P. D’yakonov V. I. Markovich V. L. Kovarskii A. V. Markovich M. Borowiec A. Jedrzejczak H. Szymczak 《Physics of the Solid State》1998,40(4):691-698
The low-temperature thermal and magnetic-resonance properties of a monoclinic KDy(WO4)2 single crystal are investigated. It is established that a structural phase transition takes place at T
c=6.38 K. The field dependence of the critical temperature is determined for a magnetic field oriented along the crystallographic
a and c axes. The initial part of the H-T phase diagram is plotted for H∥a. The prominent features of the structural phase transition are typical of a second-order Jahn-Teller transition, which is
not accompanied by any change in the symmetry of the crystal lattice in the low-temperature phase. The behavior of C(T) in a magnetic field shows that the transition goes to an antiferrodistortion phase. An anomalous increase in the relaxation
time (by almost an order of magnitude) following a thermal pulse is observed at T>T
c(H), owing to the structural instability of the lattice. A theoretical model is proposed for the structural phase transition
in a magnetic field, and the magnetic-field dependence of T
c is investigated for various directions of the field.
Fiz. Tverd. Tela (St. Petersburg) 40, 750–758 (April 1998) 相似文献
17.
We report a study of the temperature dependence, down to 30 mK, of the magnetoresistance of Cd-Sb alloy in the insulating
phase obtained by annealing the quenched metallic superconducting (
T
c
≈4.5 K) phase of the alloy. Even though the sample in this state is no longer superconducting, the observed negative magnetoresistance
points to single-particle tunneling in the presence of a superconducting gap in the spectrum. At magnetic fields B<T the ratio α(T,B)=R(T,B)/R(T,B=4 T)is found to be maximum at a temperature of about 0.1 K. This behavior indicates a change of the conductivity mechanism from
single-particle tunneling to incoherent two-particle tunneling as the temperature decreases.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 10, 713–718 (25 November 1996)
Published in English in the original Russian Journal. Edited by Steve Torstveit. 相似文献
18.
A. A. Mukhin V. Yu. Ivanov V. D. Travkin S. P. Lebedev A. Pimenov A. Loidl A. M. Balbashov 《JETP Letters》1998,68(4):356-362
The electrical conductivity, magnetic susceptibility, magnetization, and submillimeter (v=5∓20 cm−1) permittivity and dynamic conductivity of La1−x
Sr
x
MnO3 (0≤x≤ 0.45) single crystals are investigated. The anomalies in the temperature dependences of these quantities are identified
with diverse magnetic and structural phase transformations, including antiferromagnetic and ferromagnetic ordering, structural
transitions between strongly distorted (Jahn-Teller) and weakly distorted (pseudocubic) orthorhombic phases, structural transitions
to a rhombohedral phase and unusual transitions to a polaron-ordering state. As a result, the complete T-x phase diagram of the system La1−2x
Sr
x
MnO3 is constructed in a wide interval of temperatures T=4.2∓1050 K and concentrations x=0−0.45.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 4, 331–336 (25 August 1998) 相似文献
19.
V. V. Shchennikov A. E. Kar’kin N. P. Gavaleshko V. M. Frasunyak 《Physics of the Solid State》1997,39(10):1528-1532
Magnetoresistance (MR) of HgSe1−x
Sx crystals has been studied in the temperature range 4.2–300 K and in magnetic fields up to 12 T under hydrostatic pressures
P exceeding the threshold P
t for the structural phase transition. Shubnikov-de Haas quantum oscillations in longitudinal and transverse MR were observed
to occur in the original samples at T=4.2 K. For P>P
t, HgSeS crystals transferred to metastable states, which presumably incorporate the high-and low-pressure phases, and in which
the oscillations vanished. At the same time the monotonic behavior of MR with magnetic field B, as well as the temperature dependences of resistivity ρ retained the shape characteristic of the original phases. The observed weakening of the dependences of ρ on B and T is attributed to an increase of the temperature independent contribution to ρ caused by phase inclusions and structural defects in the metastable states. It is the corresponding decrease of electron
mobility that suppresses the oscillations.
Fiz. Tverd. Tela (St. Petersburg) 39, 1717–1722 (October 1997) 相似文献
20.
E. M. Levin V. K. Pecharsky K. A. Gschneidner Jr. P. Tomlinson 《Journal of magnetism and magnetic materials》2000,210(1-3)
Magnetic field (0–4 T) and temperature dependencies (4.2–320 K) of the electrical resistance of Gd5(Si1.5Ge2.5), which undergoes a reversible first-order ferromagnetic↔paramagnetic phase transition, have been measured. The electrical resistance of Gd5(Si1.5Ge2.5) indicates that the magnetic phase transition can be induced by both temperature and magnetic field. The temperature dependence of the electrical resistance, R(T), for heating at low temperatures in the zero magnetic field has the usual metallic character, but at a critical temperature of Tcr=216 K the resistance shows a 20% negative discontinuity due to the transition from the low-temperature high-resistance state to the high-temperature low-resistance state. The R(T) dependence for cooling shows a similar but positive 25% discontinuity at 198 K. The isothermal magnetic field dependence of the electrical resistance from 212T224 K indicates the presence of temperature-dependent critical magnetic fields which can reversibly transform the paramagnetic phase into the ferromagnetic phase and vice versa. The critical magnetic fields diagram determined from the isothermal magnetic field dependencies of the electrical resistance of Gd5(Si1.5Ge2.5) shows that the FM↔PM transition in zero magnetic field on cooling and heating occurs at 206 and 213 K, respectively. The full isothermal magnetic filed hysteresis for the FM↔PM transition is 2 T, and the isofield temperature gap between critical magnetic fields is 7 K. 相似文献