共查询到20条相似文献,搜索用时 656 毫秒
1.
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
2.
N. E. Sluchanko D. N. Sluchanko V. V. Glushkov S. V. Demishev N. A. Samarin N. Yu. Shitsevalova 《JETP Letters》2008,86(9):604-607
Within a wide temperature range of 1.8–300 K, the Hall effect in holmium dodecaboride is investigated. The measurements of
the angular dependences of the Hall resistance ρH(φ, T, H) for HoB12 performed in a high magnetic field up to 80 kOe at helium and intermediate temperatures made it possible to separate the
normal and anomalous contributions to the Hall effect. Analysis of the anomalous component behavior in the paramagnetic and
Néel phases suggests the appearance of the 5d-state magnetic polarization (the spin polaron effect) and makes it possible to compare the revealed features of the Hall
coefficient R
H(T, H) with the H-T magnetic phase diagram of HoB12. 相似文献
3.
Evidence that pinning on linear or planar defects dominates the vortex dynamics in YBa2Cu3O7−x (YBCO) films is provided by complex impedance measurements at temperature 8 K<T<T
c
and magnetic field 0<B<6 T. Below the vortex lattice melting transition Bg(T) but above a threshold field Bp≈8(1-T/T
c
) T, the inductance of vortices increases as B2, much less rapidly than predicted for collective pinning of vortices by point defects. Above the vortex melting line, critical
scaling persists over the region Bg(T<B<B*(T) where the vortex correlation length ξ exceeds a characteristic length scale ξ*≡ξ(B=B*)≈450?. The value of ξ* is not sensitive to Al-doping in the Cu sites in the lattice and is close to the size of twin domains in the film. The nature
of the observed crossovers is discussed in terms of available theoretical models for a glass-liquid transition at Bg. 相似文献
4.
B. I. Belevtsev V. B. Krasovitsky D. G. Naugle K. D. D. Rathnayaka Glenn Agnolet I. Felner 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(8):1049-1052
Magnetic and superconducting properties of polycrystalline samples of RuSr2Gd1.5Ce0.5Cu2O(10 − δ), asprepared (by solid-state reaction) and annealed in pure oxygen at different pressure are presented. Specific heat and
magnetization were investigated in the temperature range 1.8–300 K with a magnetic field up to 8 T. Specific heat, C (T), shows a jump at the superconducting transition (with onset at T ≈ 37.5 K) and a Schottky-type anomaly below 20 K. It is found that curves C(T) taken for different values of magnetic field have the same crossing point (at T
* ≈ 2.7 K) for all samples studied. At the same time, C(H) curves taken for different temperatures have a crossing point at a characteristic field H
* ≈ 3.7 T. These effects are manifestations of the crossing-point phenomenon, which is supposed to be inherent for strongly
correlated electron systems. 相似文献
5.
N. E. Sluchanko A. N. Azarevich A. V. Bogach I. I. Vlasov V. V. Glushkov S. V. Demishev A. A. Maksimov I. I. Tartakovskii E. V. Filatov K. Flachbart S. Gabani V. B. Filippov N. Yu. Shitsevalova V. V. Moshchalkov 《Journal of Experimental and Theoretical Physics》2011,113(3):468-482
Precision measurements of the specific heat and spectral intensity I(ω) of Raman scattering for Lu N B12 single crystal samples with various boron isotopes (N = 10, 11, nat) have been performed at low and intermediate temperatures. A boson peak in the low-frequency part of the I(ω) spectrum has been observed for the first time for lutetium dodecaboride at liquid nitrogen temperatures. It has been shown that low-temperature anomalies in the specific heat, along with the features of Raman spectra, can be interpreted in terms of the transition to a cageglass state at T* = 50?70 K, which appears when Lu3+ ions are displaced from the centrosymmetric position in cavities of a rigid covalent boron sublattice towards the randomly located boron vacancies. The concentrations of various two-level systems that correspond to two types of vibrational clusters with correlation lengths of 12–15 and 18–22 Å, respectively, have been estimated. The vibrational density of states of LuB12 has been calculated from Raman spectra in the model of soft atomic potentials. An approach has been proposed to explain the dielectrization of the properties of the YbB12 compound at T < T*, as well as the features of the formation of magnetic structures in RB12 antiferromagnets (R = Tb, Dy, Ho, Er, Tm) and the suppression of superconductivity in LuB12. 相似文献
6.
N. E. Sluchanko D. N. Sluchanko V. V. Glushkov S. V. Demishev N. A. Samarin N. Yu. Shitsevalova 《JETP Letters》2007,86(9):604-607
Within a wide temperature range of 1.8–300 K, the Hall effect in holmium dodecaboride is investigated. The measurements of
the angular dependences of the Hall resistance ρH(φ, T, H) for HoB12 performed in a high magnetic field up to 80 kOe at helium and intermediate temperatures made it possible to separate the
normal and anomalous contributions to the Hall effect. Analysis of the anomalous component behavior in the paramagnetic and
Néel phases suggests the appearance of the 5d-state magnetic polarization (the spin polaron effect) and makes it possible to compare the revealed features of the Hall
coefficient R
H(T, H) with the H-T magnetic phase diagram of HoB12.
Original Russian Text ? N.E. Sluchanko, D.N. Sluchanko, V.V. Glushkov, S.V. Demishev, N.A. Samarin, N.Yu. Shitsevalova, 2007,
published in Pis’ma v Zhurnal éksperimental’noĭ i Teoreticheskoĭ Fiziki, 2007, Vol. 86, No. 9, pp. 691–694. 相似文献
7.
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
8.
Manganese-doped ZnSiAs<Subscript>2</Subscript> chalcopyrite: A new advanced material for spintronics
L.?I.?Koroleva D.?M.?Zashchirinski? T.?M.?Khapaeva S.?F.?Marenkin I.?V.?Fedorchenko R.?Szymczak B.?Krzumanska V.?Dobrovol’ski? L.?Kilanski? 《Physics of the Solid State》2009,51(2):303-308
A new spintronics material with the Curie temperature above room temperature, the ZnSiAs2 chalcopyrite doped with 1 and 2 wt % Mn, is synthesized. The magnetization, electrical resistivity, magnetoresistance, and
the Hall effect of these compositions are studied. The temperature dependence of the electrical resistivity follows a semiconducting
pattern with an activation energy of 0.12–0.38 eV (in the temperature range 124 K ≤ T ≤ 263 K for both compositions). The hole mobility and concentration are 1.33, 2.13 cm2/V s and 2.2 × 1016, 8 × 1016 cm−3 at T = 293 K for the 1 and 2 wt % Mn compositions, respectively. The magnetoresistance of both compositions, including the region
of the Curie point, does not exceed 0.4%. The temperature dependence of the magnetization M(T) of both compositions exhibits a complicated character; indeed, for T ≤ 15 K, it is characteristic of superparamagnets, while for T > 15 K, spontaneous magnetization appears which correspond to a decreased magnetic moment per formula unit as compared to
that which would be observed upon complete ferromagnetic ordering of Mn2+ spins or antiferromagnetic ordering of spins of the Mn2+ and Mn3+ ions. Thus, for T > 15 K, it is a frustrated ferro- or ferrimagnet. It is found that, unlike the conventional superparamagnets, the cluster
moment μ
c
in these compositions depends on the magnetic field: ∼12000–20000μB for H = 0.1 kOe, ∼52–55μB for H = 11 kOe, and ∼8.6–11.0μB at H = 50 kOe for the compositions with 1 and 2 wt % Mn, respectively. The specific features of the magnetic properties are explained
by the competition between the carrier-mediated exchange and superexchange interactions. 相似文献
9.
The NMR of 55Mn in the quasi-one-dimensional noncollinear anti-ferromagnet CsMnI3 is investigated at T=1.3 K in magnetic fields up to ∼80 kOe and angles between the field and C
6 axis ϕ≈ 0.5° and ϕ=7°. A new reorientational magnetic phase transition is observed in a field H
c1≈39.0 kOe. The magnetic structure for H>H
c1 is determined. The average Mn2+ spins of the magnetic sublattices in the new phase are determined from an analysis of the NMR spectrum to be 〈 S
C
〉=1.63 and 〈S
D
〉=1.72.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 12, 988–993 (25 June 1998) 相似文献
10.
D. A. Balaev A. A. Dubrovskiy S. I. Popkov K. A. Shaikhutdinov O. N. Mart’yanov M. I. Petrov 《Journal of Experimental and Theoretical Physics》2010,110(4):584-593
The transport properties (R(T) and R(H) dependences at various values of the transport current in magnetic fields up to 65 kOe) and low-temperature heat capacity
in magnetic fields up to 90 kOe of the BaPb0.75Bi0.25O3 superconductor (T
C
≈ 11.3 K) are investigated with the goal of clarifying the mechanisms determining the nonmonotonic behavior and hysteresis
of its magnetoresistance R(H). The type of R(H) hysteretic dependences for BaPb0.75Bi0.25O3 is analogous to that observed in granular high-T
c
superconductors (HTSCs); however, unlike classical HTSC systems, the field width of the magnetoresistance hysteresis loop
for polycrystalline BaPb0.75Bi0.25O3 depends on the transport current. This means that although the mechanisms responsible for the magnetoresistance hysteresis
(the influence of the magnetic flux trapped in superconducting regions on the effective field in Josephson interlayers) are
identical in these objects, the transport current in BaPb0.75Bi0.25O3 may considerably affect the diamagnetic response of the superconductor. A considerable effect of transport current on the
field in which the R(H) dependences have a peak and exhibit hysterestic properties is observed. Such a behavior can be adequately interpreted using
the model of the spatially inhomogeneous superconductor-insulator state proposed by Gorbatsevich et al. [JETP Lett. 52, 95 (1990)]. The nonmonotonic dependence of quantity C/T (C is the heat capacity) on the magnetic field discovered in the present study also agrees with the conclusions based on this
model. 相似文献
11.
H.-F. Li Y. Su Y. G. Xiao J. Persson P. Meuffels Th. Brückel 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,67(2):149-157
A neutron powder diffraction (NPD) study on the crystal and magnetic structure of a crushed La1-xSrxMnO3 (x ≈ 1/8) single crystal has been performed. The sample belongs to orthorhombic (Pnma, O) above the Jahn-Teller (JT) transition temperature (TJT) and monoclinic (P121/c1, M′) in the JT regime. We have also refined the NPD data below the charge/orbital ordering (CO/OO) temperature (TCO/OO) with a monoclinic (P121/c1, M′′) model because the experimental resolution was insufficient to clearly identify a triclinic structure. The refined lattice parameters show an obvious breathing-mode distortion between TCO/OO and TJT, accompanied by a large deviation of the monoclinic angle β from 90°, signifying a very strong cooperative JT distortion.
A ferromagnetic (FM) moment of 3.43(5)μ
B/Mn besides an A-type antiferromagnetic (A-AFM) moment of 0.54(2) μ
B/Mn is directed mainly along the b axis in P121/c1 symmetry at 5 K. With increasing temperature, the A-AFM domains transform into FM ones above ~100 K and the FM spin orientation
turns from the b to the c axis in crystallographic b-c plane below Tc = 187(1) K. The magnetization measurements show typical anomalies around TCO/OO and TJT. The measured saturation moment of 3.9(1)μ
B/Mn at 70 kOe and 5 K is well consistent with the sum 3.97(5)μ
B/Mn of the refined FM and A-AFM moments at 5 K, implying the A-AFM spins are aligned in field direction at 70 kOe. The applied
magnetic field can affect the paramagnetic insulating (PMI) state in the range of magnetic polarons. Based on the size of
JT distortion and the bond-valence sums (BVS’s), the CO/OO phenomenon is being discussed. 相似文献
12.
N. I. Solin 《Journal of Experimental and Theoretical Physics》2012,114(1):96-106
The nature of the electrical resistivity for low-doped lanthanum manganites is elucidated. The electrical resistivity is described
by the Efros-Shklovskii law (lnρ √ (T
0/T)−1/2, where T
0 √ 1/R
ls) in the temperature range from T* ≈ 300 K ≈ T
C (T
C is the Curie temperature for conducting manganites) to their T
C and is explained by the tunneling of carriers between localized states. The magnetoresistance is explained by a change in
the size of localized states R
ls in a magnetic field. The patterns of change in R
ls with temperature and magnetic field strength determined from magnetotransport properties are satisfactorily described in
the model of phase separation into small-radius metallic droplets in a paramagnetic matrix. The sizes R
ls and their temperature dependence have been estimated through magnetic measurements. The results confirm the existence of
a Griffith phase. The intrinsic inhomogeneities produced by thermodynamic phase separation determine the electrical resistivity
and magnetoresistance of lanthanum manganites. 相似文献
13.
N. E. Sluchanko V. V. Glushkov S. V. Demishev M. V. Kondrin N. A. Samarin V. V. Brazhkin I. Braunserade V. V. Moshchalkov 《Physics of the Solid State》1999,41(1):1-7
Galvanomagnetic characteristics of the A1−x
Six solid solutions (x<12 at. %) have been studied within a broad range of temperatures (1.8–290 K) and magnetic fields (up to 15 T). An anomaly
in the concentration dependence of the Hall coefficient R
H
(x,T=290 K) has been revealed near the boundary of absolute instability (x<8.5 at. %) of compounds in the Al1−x
Six series. The variation of the Hall coefficient and of the magnetoresistance in the A1−x
Six series at low (T<77 K) temperatures is analyzed within models taking into account the anisotropy in conduction-band electron scattering.
Fiz. Tverd. Tela (St. Petersburg) 41, 3–10 (January 1999) 相似文献
14.
D. M. Zashchirinskii L. I. Koroleva A. S. Morozov Yu. V. Dolzhenkova 《Physics of the Solid State》2011,53(2):316-319
The magnetocaloric effect ΔT has been studied by a direct method in two samples of the manganite Sm0.55Sr0.45MnO3, namely, a single crystal (sample A) and a ceramic sample (sample C). The temperature dependences of the ΔT effect of both samples exhibit a maximum at T
max = 143.3 K for the sample A and T
max = 143 K for the sample C. In these maxima, the values of the ΔT effect are 0.8 and 0.4 K in the magnetic field H = 14.2 kOe for the samples A and C, respectively. In addition, the ΔT(T) curve of the sample A has a minimum at T
min = 120 K, in which ΔT = −0.1 K. The maximum value of the ΔT effect increases with an increase in the magnetic field H in the range of magnetic fields up to 14.2 kOe, and the rate of this increase at H > 8 kOe is higher than that at H < 8 kOe. These features of the ΔT effect are explained by the presence of ferromagnetic and antiferromagnetic A- and CE-type clusters in the samples. 相似文献
15.
V. A. Ryzhov P. L. Molkanov A. V. Lazuta V. V. Runov V. P. Khavronin I. O. Troyanchuk 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(10):1477-1480
We present the results from studying the magnetic properties (linear and nonlinear susceptibilities and the depolarization
of polarized neutrons) of Nd1 − x
Ba
x
MnO3 manganite, x = 0.3, with Curie temperature T
C ≈ 140 K and dielectric-to-metal transition temperature T
DM ≈ 129 K. Its critical behavior corresponds to that of an isotropic 3-D ferromagnet at temperatures above T*≈ 144 K, but a strong nonlinear response in weak magnetic fields and depolarization are observed at temperatures below T*. It is shown that this nontraditional behavior is related to the generation of ferromagnetic clusters in the paramagnetic
matrix that form a conducting percolative network at temperatures near T
DM. 相似文献
16.
V. V. Popov P. P. Konstantinov Yu. V. Rud’ 《Journal of Experimental and Theoretical Physics》2011,113(4):683-691
Electrical resistivity ρ and Hal coefficient R are measured as a function of the temperature (T = 1.7−310 K) and the magnetic field (up to H = 28 kOe) in zero-gap semiconductor CuFeS2 samples subjected to hydrostatic compression and under various heat-treatment conditions. At low temperatures, anomalies
are observed in the kinetic effects related to the presence of ferromagnetic clusters: the magnetoresistance at T = 4.2 K and T = 20.4 K acquires a hysteretic character and thermopower α changes its sign at T < 15 K. The temperature dependence of conduction-electron concentration n in CuFeS2 has a power form in the temperature range T = 14−300 K, which is characteristic of the intrinsic conductivity in zero-gap semiconductors. In CuFeS2, we have n(T) ∝ T
1.2; in isoelectron compound Cu1.13Fe1.22Te2, we have n(T) ∝ T
1.93. Heat treatment is found to affect the intrinsic conductivity of CuFeS2, as the action of hydrostatic compression (carrier concentration changes); that is, the carrier concentration changes. However,
a power form of the n(T) and ρ(T) dependences is retained. 相似文献
17.
G. A. Petrakovskii K. A. Sablina A. M. Vorotynov O. A. Bayukov A. F. Bovina G. V. Bondarenko R. Szymczak M. Baran H. Szymczak 《Physics of the Solid State》1999,41(4):610-612
The temperature dependence of the magnetic susceptibility of Cu3B2O6 single crystals grown by spontaneous crystallization from a melt consisting of a mixture of CuO and B2O3 and the behavior of their magnetization are investigated in magnetic fields up to 55 kOe. A broad susceptibility maximum
is observed near 39 K, and a sharp drop in susceptibility is observed at T<10 K. The paramagnetic Néel temperatures for all orientations of the magnetic field in the crystal investigated are negative,
attesting to the predominantly antiferromagnetic character of the exchange interactions. The effective magnetic moment of
the Cu2+ ion is anisotropic and lies in the range from 1.054μ
B to 1.545μ
B. The magnetization depends linearly on magnetic field at T>10 K, whereas at temperatures below 10 K a discontinuity is observed at fields of the order of 40 kOe. At room temperature,
electron magnetic resonance characterized by an almost isotropic g factor (g=2.165) is detected at 36.22 GHz. The exchange interactions in Cu3B2O6 are analyzed on the basis of the Goodenough-Kanamori rules. The possibility of the establishment of a singlet magnetic state
in the crystal is analyzed.
Fiz. Tverd. Tela (St. Petersburg) 41, 677–679 (April 1999) 相似文献
18.
M. K. Aliev G. R. Alimov T. M. Muminov B. A. Olimov Kh. I. Turkmenov I. Kholbaev L. I. Leonyuk R. F. Rumi 《Physics of the Solid State》1999,41(1):11-14
Y1Ba2Cu3O7−x
single crystals are investigated near T
c
≈92 K in fields 0<H⩽9 kOe using a modified ESR spectrometer. The temperature modulation method is used for the first time, together with the
traditional magnetic modulation method, to detect microwave responses in single crystals. Superconducting-transition peaks
shifted relative to one another in temperature and differing in shape are observed in the temperature dependence of the corresponding
signals ∂R/∂H and ∂R/∂T (R — microwave absorption). The evolution of these peaks as a function of the field and the angle π between H and the c axis of the single crystal is traced. It is shown that the difference in the temperature dependences of the derivatives ∂R/∂H and ∂R/∂T is due to the broadening of the superconducting transition characteristic of HTSCs.
Fiz. Tverd. Tela (St. Petersburg) 41, 14–17 (January 1999) 相似文献
19.
V. S. Zakhvalinski? R. Laiho T. S. Orlova A. V. Khokhulin 《Physics of the Solid State》2008,50(1):63-70
The temperature dependences of the magnetic susceptibility χ(T) and the electrical resistivity ρ(T) of ceramic samples of La1 − x
Ca
x
MnO3 with x = 0.67 (LCMO) and La1 − x
Ca
x
Mn1 − y
Fe
y
O3 with x = 0.67 and y = 0.05 (LCMFO) are investigated in magnetic fields B = 50–105 G and the temperature range T = 4.2–400 K. Both samples undergo a transition from the paramagnetic state to a state with charge (orbital) ordering (CO)
at temperatures T
CO ≈ 272 K for LCMO and T
CO ≈ 222 K for LCMFO. The behavior of the paramagnetic phase in the temperature range 320–400 K for LCMO and 260–400 K for LCMFO
is described by the Curie-Weiss law with effective Bohr magneton numbers p
eff = 4.83 μB (LCMO) and 4.77 μB (LCMFO), respectively. The disagreement between the observed positive Weiss temperatures (θ ≈ 175 K (LCMO) and θ ≈ 134 K
(LCMFO)) and negative Weiss temperatures required for the antiferromagnetic ground state can be explained by the phase separation
and transition to the charge-ordered state. The magnetic irreversibility for T < T
CO is accounted for by the existence of a mixture of the ferromagnetic and antiferromagnetic phases, as well as the cluster
glass phase. At low temperatures, doping with iron enhances the frustration of the system, which manifests itself in a more
regular behavior of the decay rate of the remanent magnetization with time. The temperature dependence of the electrical resistivity
in the range of the charge-ordered phase conforms to the variable-range hopping model. The behavior of the electrical resistivity
is governed by the complex structure of the density of localized states near the Fermi level, which includes a soft Coulomb
gap Δ = 0.464 eV for LCMO and 0.446 eV for LCMFO. It is established that the ratio between the localization radii of charge
carriers a for LCMFO and a
und for LCMO is a/a
und = 0.88.
Original Russian Text ? V.S. Zakhvalinskiĭ, R. Laiho, T.S. Orlova, A.V. Khokhulin, 2008, published in Fizika Tverdogo Tela,
2008, Vol. 50, No. 1, pp. 61–68. 相似文献
20.
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