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1.
A. D. Bozhko A. N. Vasil’ev V. V. Khovailo V. D. Buchel’nikov I. E. Dikshtein S. M. Seletskii V. G. Shavrov 《JETP Letters》1998,67(3):227-232
The phase diagram of the cubic ferromagnetic shape-memory alloy Ni2+x
Mn1−x
Ga is constructed theoretically for the case when the Curie temperature is close to the structural transition temperature.
This diagram agrees well with the experimental data obtained from resistance and magnetic susceptibility measurements. It
is shown that the transition from the paramagnetic cubic phase to the ferromagnetic tetragonal phase can be second-order or
first-order.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 3, 212–216 (10 February 1998) 相似文献
2.
V. S. Gaviko V. E. Arkhipov A. V. Korolev V. E. Naish Ya. M. Mukovskii 《Physics of the Solid State》1999,41(6):969-973
A study is made of phase transitions in doped La0.9Sr0.1MnO3 compounds using combined x-ray, electrical, and magnetic measurements. Structural phase transitions are observed accompanied
by a change in the cell volume at temperatures of 100–110 K and 300–340 K. These structural changes are found to be related
to different contributions of the rhombic Jahn-Teller Q
2 mode to the formation of the crystal lattice. The structural transition at 100–110 K is accompanied by distinctive magnetic
and electrical properties. The data are analyzed in detail.
Fiz. Tverd. Tela (St. Petersburg) 41, 1064–1069 (June 1999) 相似文献
3.
A. V. Klochkov V. V. Naletov I. R. Mukhamedshin M. S. Tagirov D. A. Tayurskii H. Suzuki 《JETP Letters》1997,66(4):266-270
The field (0–5.5 T) and temperature (2–300 K) dependences of the magnetization of LiTmF4 powders with particle sizes of 1 μm and 56–400 μm are investigated experimentally and theoretically. It is concluded that
a transition layer exists between the thulium ions in the bulk and the ions at the surface. Two magnetic-field-induced structural
phase transitions are observed at low temperatures, and the temperature dependence of the critical magnetic fields is established.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 4, 247–250 (25 August 1997) 相似文献
4.
A. D. Bozhko A. N. Vasil’ev V. V. Khovailo I. E. Dikshtein V. V. Koledov S. M. Seletskii A. A. Tulaikova A. A. Cherechukin V. G. Shavrov V. D. Buchel’nikov 《Journal of Experimental and Theoretical Physics》1999,88(5):954-962
The results of an experimental investigation of the temperature dependences of the magnetic susceptibility and resistivity
in the shape-memory ferromagnetic alloys Ni2+x
Mn1−x
Ga (x=0–0.20) are reported. A T−x phase diagram is constructed on the basis of these data. It is shown that partial substitution of Ni for Mn causes the temperatures
of the structural (martensitic) T
M
and magnetic T
C
(Curie point) phase transitions to converge. In the region where T
C
=T
M
the transition temperature increases linearly with magnetic field in the range from 0 to 10 kOe. The kinetics of a magnetic-field-induced
martensitic phase transition is investigated, and the velocities of the martensite-austenite interphase boundary during direct
and reverse transitions are measured. A theoretical model is proposed and the T−x phase diagram is calculated. It is shown that there exist concentration ranges where the magnetic and martensitic transitions
merge into a first-order phase transition. The theoretical results are in qualitative agreement with experiment.
Zh. éksp. Teor. Fiz. 115, 1740–1755 (May 1999) 相似文献
5.
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
6.
M. Balagurov V. Yu. Pomyakushin V. L. Aksenov N. M. Plakida N. A. Babushkina L. M. Belova O. Yu. Gorbenko A. R. Kaul’ P. Fischer M. Gutmann L. Keller 《JETP Letters》1998,67(9):705-711
The evolution of the structural and magnetic properties of the CMR (colossal-magnetoresistance) compound La0.35Pr0.35Ca0.30MnO3 as the temperature changes from 10 to 293 K is investigated by means of neutron diffraction. It is shown that the changes
in the transport and magnetic properties are directly related with the rearrangement of the atomic structure. A phase transition
to the metallic state occurs together with simultaneous ferromagnetic ordering of the manganese moments and is accompanied
by a jump in volume. The static distortions of the oxygen octahedra which are observed to occur prior to the magnetic phase
transition and which are practically absent at room temperature and in the FM phase attest to the orbital ordering of oxygen
atoms on the bonds, with freezing-in of the Jahn-Teller modes.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 9, 672–677 (10 May 1998) 相似文献
7.
S. A. Nemov M. K. Zhitinskaya R. V. Parfen’ev D. V. Shamshur 《Physics of the Solid State》1998,40(7):1096-1097
A study is reported of the effect of low-level germanium additions (∼0.01–0.1 at. %) on the parameters of the superconducting
transition, viz. the critical temperature T
c, the second critical magnetic field H
c2, and
in PbTe doped with 2 at. % Tl, which are derived from the dependence of the electrical resistivity of a sample on temperature
(0.4–4.2 K) and magnetic field (0–1.3 T). The discontinuity revealed by experimental data is related to the onset of a Ge-induced
structural phase transition.
Fiz. Tverd. Tela (St. Petersburg) 40, 1204–1205 (July 1998) 相似文献
8.
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
9.
G. A. Petrakovskii L. I. Ryabinkina D. A. Velikanov S. S. Aplesnin G. M. Abramova N. I. Kiselev A. F. Bobina 《Physics of the Solid State》1999,41(9):1520-1524
Experimental-theoretical studies were carried out of the electrical and magnetic properties of the antiferromagnetic semiconductor
Cr0.5Mn0.5S in the temperature range 4.2–300 K. A magnetic antiferromagnetic-ferrimagnetic phase transition was observed along with
a semimetalsemiconductor electronic transition. Monte Carlo calculations indicate that the changes in the type of magnetic
ordering and conductivity are due to the cooperative Jahn-Teller effect caused by the Cr2+ ions.
Fiz. Tverd. Tela (St. Petersburg) 41, 1660–1664 (September 1999) 相似文献
10.
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
11.
The specific heat of Pb2MgWO6 has been measured in the temperature interval 83–370 K. An anomaly in the specific heat associated with the phase transition
at T
0=312.8K has been discovered. The thermodynamic parameters of the structural phase transition Fm3m-Pmcn have been determined.
Fiz. Tverd. Tela (St. Petersburg) 41, 1686–1688 (September 1999) 相似文献
12.
G. A. Takzei M. V. Gavrilenko I. I. Sych P. Esquinazi L. M. Kulikov 《Physics of the Solid State》1997,39(10):1607-1611
A study of the dynamic and static magnetic susceptibility of quasi-two-dimensional, doubly intercalated compounds Cr1/3−x
NixTaS2 (0.08⩽x⩽0.23) is reported. It is shown that cooling from paramagnetic phase in this concentration range produces a spin-glass-type
frozen magnetic state. In contrast to the classical 3D spin glasses, however, this state sets in within a broad temperature
range rather than at a phase transition. A magnetic phase diagram of the studied compounds has been constructed.
Fiz. Tverd. Tela (St. Petersburg) 39, 1801–1805 (October 1997) 相似文献
13.
This paper discusses how temperature/pressure processing affects the cascade of magnetic phase transitions in the alloy Fe0.5Mn1.1As with a C38 tetragonal crystal lattice. It shows that after various temperature/pressure treatment regimes (quenching of the sample
from 800 °C under pressures of 30–60 kbar) no transition to the low-temperature phase is observed, as a result of which the
ferrimagnetic phase extends to liquid-nitrogen temperatures. These results are analyzed on the basis of a qualitative model
that takes into account the competition of ferromagnetic and antiferromagnetic interactions within and between nonequivalent
crystallographic subsystems.
Fiz. Tverd. Tela (St. Petersburg) 39, 889–893 (May 1997) 相似文献
14.
R. I. Zainullina N. G. Bebenin V. V. Ustinov 《Journal of Experimental and Theoretical Physics》1997,85(2):376-380
We report on the detection of two narrow peaks of positive magnetoresistivity in the temperature dependence of the magnetoresistivity
of a Fe0.95Co0.05Ge2 single crystal in the vicinity of a “smeared” first-order phase transition. The position of these peaks correlates with the
position of singularities in the temperature dependence of the temperature derivative of the electrical resistivity and magnetic
susceptibility. We show that these singularities in the transport and magnetic properties are, probably due to the presence
of two percolation transitions with temperature in the magnetic subsystem of the crystal.
Zh. éksp. Teor. Fiz. 112, 690–697 (August 1997) 相似文献
15.
G. V. Loseva L. I. Ryabinkina S. S. Aplesnin A. D. Balaev A. F. Bovina A. M. Vorotynov K. I. Yanushkevich 《Physics of the Solid State》1997,39(8):1267-1270
A study of the structure and electrical and magnetic properties of the VxMn1−x
S disordered system is reported. The existence of a low-temperature metal-insulator transition for Fermi-glass 0.4<x<0.5 compositions in paramagnetic phase, which is accompanied by a change in the structure and magnetic properties, has been
established. An analysis of the magnetic properties permits a conjecture that current carriers become delocalized in these
solid solutions at the metal-insulator transition temperature to form small ferromagnetically ordered regions (ferrons).
Fiz. Tverd. Tela (St. Petersburg) 39, 1428–1431 (August 1997) 相似文献
16.
I. O. Troyanchuk N. V. Samsonenko G. Shimchak A. Nabyalek 《Physics of the Solid State》1997,39(1):101-103
The magnetic properties of Eu1−x
CaxMnO3 have been investigated. As the calcium content increased up to x=0.2, the magnetization and the blocking temperature of the magnetic moments of clusters increased and the magnetic anisotropy
decreased. As the calcium content increased further, the magnetization decreased, while the “freezing” temperature of the
magnetic moments increased. Anomalies of the magnetic properties were observed in compositions with x=0.4 and 0.5 at T=40 K; these anomalies are attributed to a transition to the antiferromagnetic state in the charge-ordered phase.
Fiz. Tverd. Tela (St. Petersburg) 39, 117–120 (January 1997) 相似文献
17.
Z. A. Kazei V. V. Snegirev A. S. Andreenko L. P. Kozeeva 《Journal of Experimental and Theoretical Physics》2011,113(2):245-250
The elastic properties of rare-earth cobaltites RBaCo4O7 (R = Y, Tm-Lu) have been experimentally studied in the temperature range of 80–300 K. The strong softening of the Young modulus
ΔE(T)/E
0 ≈ −(0.1–0.2) of cobaltites with Lu and Yb ions has been revealed, which is due to the instability of the crystal structure
upon cooling and is accompanied by an inverse jump at the second-order structural phase transition. The softening of the Young
modulus and the jump at the phase transition decrease by an order of magnitude and the transition temperature T
s and hysteresis ΔT
s increase from a compound with Lu to that with Tm. A large softening of the Young modulus at the structural transition in
Lu- and Yb cobaltites indicates that the corresponding elastic constant goes to zero, whereas this constant in Tm cobaltite
is not a “soft” mode of the phase transition. It has been found that the structural phase transition in Lu- and Yb cobaltites
is accompanied by a large absorption maximum at the phase transition point and an additional maximum in the low-temperature
phase and absorption anomalies in Tm cobaltite is an order of magnitude smaller. 相似文献
18.
N. E. Sluchanko A. N. Azarevich A. V. Bogach S. Yu. Gavrilkin V. V. Glushkov S. V. Demishev A. V. Dukhnenko A. B. Lyashchenko K. V. Mitsen V. B. Filipov 《JETP Letters》2011,94(8):642-646
The specific heat of the ZrB12 compound in the normal and superconducting states (T
C
≈ 6 K) has been studied in the 1.9–7 K temperature range for high-quality single crystals with different relative contents
of boron isotopes. For Zr10B12, ZrnatB12, and Zr11B12 dodecaborides, the electron density of states and the electronphonon coupling constant, λe-ph ∼ 0.4, are found. The dependence of the thermodynamic and upper critical fields, as well as of the Ginzburg-Landau parameter
(κ = 0.8–1.14) on temperature and isotope composition is determined. The results suggest the existence of the magnetic field
induced phase transition at T* = 4–5 K, which is not related to the transition from type-I to type-II superconductivity. The possibilities of the existence
of two-gap superconductivity and a structural phase transition at T* in zirconium dodecaboride are discussed. 相似文献
19.
This paper discusses experimental studies of the temperature dependence of the magnetic susceptibility, electrical conductivity,
and Seebeck coefficient of the compounds CoxTiSe2 (0.1⩽x⩽0.5), along with the structural behavior exhibited by these compounds. For Co0.5TiSe2, the observed temperature dependence of the magnetic susceptibility is characteristic of an antiferromagnet with a Néel temperature
of 510 K. The data obtained on the structural characteristics and physical properties of the intercalated phases are interpreted
using a model that assumes the formation of bands of localized states near the Fermi level.
Fiz. Tverd. Tela (St. Petersburg) 39, 1618–1621 (Sepember 1997) 相似文献
20.
B. A. Strukov E. P. Ragula S. Yu. Stefanovich I. V. Shnaidshtein S. V. Arkhangel’skaya A. Onodera 《Physics of the Solid State》1998,40(7):1193-1195
The specific heat of the ceramic and the permittivity of a single-crystal sample of LaBSiO5, a new ferroelectric in the stilwellite family, were measured in a temperature range which includes the phase transition
point (T
C=140 °C). The excess entropy of the phase transition ΔS=1.05 J/mol · K and the Curie-Weiss constant C
C-W=3.2×103 K were determined. The results indicate that the phase transition in this crystal is of a “mixed” nature and exhibits features
of a displacement-type transition and an order-disorder transition.
Fiz. Tverd. Tela (St. Petersburg) 40, 1310–1312 (July 1998) 相似文献