共查询到20条相似文献,搜索用时 78 毫秒
1.
Mahdi S. Lataifeh 《Applied Physics A: Materials Science & Processing》2008,92(3):681-685
The saturation magnetization (M
s) and the initial magnetic susceptibility (χ
in) of substituted yttrium iron garnet (YIG) Ho3−x
Y
x
Fe5O12 where (x=0,0.3,1.5), pure terbium iron garnet Tb3Fe5O12, and substituted aluminum iron garnet (AlIG) Ho3Fe5−x
Al
x
O12 where (x=0.05,0.7) at room temperature are reported. It has been observed that M
s and χ
in decrease in a linear manner as Ho3+ replaces Y3+ in yttrium iron garnet. For substituted (AlIG), a drastic decrease in both M
s and χ
in as Al3+ ions replace Fe3+ ions. The rate of decrease of M
s and χ
in with the increase of Al3+ for substituted (AlIG) is greater than that for substituted (YIG). That is attributed to the decrease in the superexchange
interaction (self and mutual iron interactions) with Al substitution. 相似文献
2.
Zero field μSR has been used to probe rare earth spin dynamics in the magnetic superconductors, Y1−x
Er
x
Ni2B2C. The muon spin relaxation function is stretched exponential, exp (−(λt)β), in form, as usually found for spin glass systems above the glass temperature. However, the Y1−x
Er
x
Ni2B2C compounds show no evidence of coexisting superconducting and static spin glass ground states even at concentrations below
the critical value (x=0.6) for long range antiferromagnetic order. The temperature dependence of both the muon spin relaxation rate λ and the exponent
β suggests that Er spin dynamics change significantly at the superconducting transition temperature.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
3.
The heat capacity of pseudobinary intermetallic compounds Gd1−x
Y
x
Ni2 (0≤x≤1) has been studied. The magnetic contribution to the total heat capacity is isolated with the use of the data obtained for
the paramagnetic analogs Lu1−y
Y
y
Ni2 possessing the same molar masses as the gadolinium compounds. It has been found that the difference between the entropies
of the Gd1−x
Y
x
Ni2 (x<0.8) compounds and the corresponding paramagnetic Lu1−y
Y
y
Ni2 analogs reaches larger values than those expected from the calculations performed under the assumption that only Gd ions
contribute to the magnetic part of the total entropy. The existence of an additional contribution of magnetic nature to the
entropy of the Gd1−x
Y
x
Ni2 compounds, as well as the large values of the γ coefficient in the linear-in-temperature term of the heat capacity, is assigned
to the spin fluctuations induced by the f—d exchange in the subsystem of Ni 3d electrons. 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.
B. Gao J. Shen F. X. Hu J. Wang J. R. Sun B. G. Shen 《Applied Physics A: Materials Science & Processing》2009,97(2):443-447
The influence of Cu substitution for Mn on magnetic properties and magnetic entropy change has been investigated in Heusler
alloys, Ni50Mn35−x
Cu
x
Sn15 (x=2,5 and 10). With increasing Cu content from x=2 to x=5, the martensitic transition temperature, T
M
, decreases from 220 K to 120 K. Further increasing Cu up to x=10 results in the disappearance of T
M
. For samples Ni50Mn33Cu2Sn15 and Ni50Mn30Cu5Sn15, both martensitic and austenitic states exhibit ferromagnetic characteristics, but the magnetization of martensitic phase
is notably lower than that of austenitic phase. The magnetization difference, ΔM, across the martensitic transition leads to a considerably large Zeeman energy, μ
0ΔM⋅H, which drives a field-induced metamagnetic transition. Associated with the metamagnetic behavior, a large positive magnetic
entropy change ΔS takes place around T
M
. For the sample Ni50Mn33Cu2Sn15,ΔS reaches 13.5 J/kg⋅K under a magnetic field change from 0 to 5 T. 相似文献
6.
W. J. Kossler X. H. Yu A. Greer H. E. Schone C. E. Stronach M. Davis R. S. Cary J. E. Crow W. F. Lankford J. Oostens 《Hyperfine Interactions》1991,63(1-4):81-86
Transverse and zero-field μSR measurements were made on YBa2(Cu1−xNix)3O7−y withx=0.1 and 0.2, and YBa2(Cu1−x
Zn
x
)3O7−y
withx=0.03, 0.06, 0.1, and 0.16, wherey≈0.1. Since doping may lead to magnetic ordering this was searched for with both zero and transverse field μSR, but no evidence
was found over the temperature range studied: 10–100 K. However, depolarization rates as functions of temperature were obtained,
and the low temperature values of these are σ=3.2 μs−1.1.6μs−1, and 1 μs−1 forx=0.01, and 0.2 Ni, respectively, and σ=0.8 μs−1, 0.75 μs−1, 0.65 μs−1, and 0.4 μs−1 forx=0.03, 0.06, 0.1, and 0.16 Zn, respectively. Estimates for the effect of decreasing electron concentration for Zn are made,
but these alone do not account for the drop in σ. Estimates for the effect of scattering on λ and hence σ are made. The reduction
in σ for Ni dopant is in surprisingly good agreement with these estimates. For Zn the order of magnitude is correct, but the
relative lack of further change in σ after the effect of the first 0.03 addition seems to imply a saturation of the effect
of scattering. 相似文献
7.
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
8.
The Ni2 + x
Mn1 − x
Ga magnetic shape memory alloys at concentrations x = 0.18–0.36 have been studied using small-angle polarized neutron scattering in magnetic fields 0 < H ≤ 5.7 kOe. In this concentration range, the alloy undergoes a coupled magnetic-structural phase transition. At x < 0.18, the martensitic phase transition occurs, as usual, in the ferromagnetic state, i.e., T
m
< T
C (T
m
and T
C are the temperatures of the martensitic and magnetic phase transitions, respectively). However, at x > 0.27, the relationship between the characteristic temperatures is changed, i.e., T
m
> T
C. The small-angle polarized neutron scattering data indicate that, in the concentration range under investigation, there occurs
a complex transformation of the magnetic and atomic structures. All phase transitions exhibit a temperature hysteresis of
scattering and polarization, which is characteristic of first-order phase transitions. A comparative analysis of the mesoscopic
structures of the Ni2 + x
Mn1 − x
Ga and Ni2 + x + y
Mn1 − x
Ga1 − y
alloys studied using the small-angle polarized neutron scattering technique has been carried out. 相似文献
9.
Electric conductivity of nitrobenzene soluted inn-hexane,n-heptane andn-octane was studied in constant and alternative field. Phase coexistence curves were determined together with the critical
temperature, critical concentration and critical exponentβ for each of the systems. The measurements were performed in the temperature rangeT
s
<T < (T
s
+ 10)K and for the concentrations of nitrobenzene between 0·2 ≲x
2 ≲ 0·7 molar fraction. 相似文献
10.
R. Cywinski S. H. Kilcoyne S. F. J. Cox C. A. Scott O. Schärpf 《Hyperfine Interactions》1991,64(1-4):427-433
Neutron polarisation analysis measurements reveal antiferromagnetic spin correlations persisting to temperatures of 120 K
in Pauli paramagnetic Y(Mn1−x
Fe
x
)2, 0.03≤x≤0.05. The mean moment at the Mn(Fe) site is found to be 0.2μ
B. Transverse field μSR is characterised by weak exponential damping with a rate of 0.02 μs−1 at 300 K increasing according to the power lawT
−0.75 to only 0.16μ
S
−1
at 12 K. It is suggested that these results are consistent with a slowing down of longitudinal spin fluctuations at the Mn
site as temperature decreases. 相似文献
11.
N. V. Rama Rao R. Gopalan V. Chandrasekaran K. G. Suresh 《Applied Physics A: Materials Science & Processing》2010,99(1):265-270
Low field inverse magnetocaloric effect (IMCE) associated with first-order martensitic transition in Ni50−x
Mn37+x
In13 (x=3,4,5) alloys was investigated. By tuning the composition of Ni/Mn, large change in the magnetization occurring between martensite
and austenite phases in a narrow temperature interval was achieved, which results in large IMCE. Under low magnetic field
change of 2 T, a large positive magnetic entropy change (ΔS
M
) of 23.5 J/kg K with a net refrigeration capacity of 53 J/kg was obtained near room temperature (308 K) in the x=3 alloy. The results show that a small variation in Ni/Mn ratio significantly influences the martensitic transition temperature
and the associated magnetic and magnetocaloric properties. 相似文献
12.
A. Pösinger W. Steiner M. Reissner H. Winkler A. X. Trautwein 《Hyperfine Interactions》1991,67(1-4):621-626
The cluster glass Y(Fe
x
Al1−x
)2,x=0.75, 0.65 and 0.40 was investigated in external fields between 4.5 and 13.5 T at temperatures above the freezing temperatureT
f. To explain the relaxation effects, which dominate the magnetic behaviour up toT∼7·T
f, a model is proposed, where magnetic clusters are formed stochastically and decay after a mean life time. 相似文献
13.
The low-temperature dc mobility of the two-dimensional electron system localized above the surface of superfluid helium is
determined by the slowest stage of the longitudinal momentum transfer to the bulk liquid, namely, by the interaction between
the surface and volume excitations of liquid helium, which decreases rapidly with the temperature. Thus, the temperature dependence
of the low-frequency mobility is μdc ≈ 8.4 × 10−11
n
e
T
−20/3 cm4 K20/3/(V s), where n
e
is the surface electron density. The relation T
20/3 E⊥−3 ≪ 2 × 10−7 between the pressing electric field (in kilovolts per centimeter) and temperature (in Kelvins) and the value ω ≲ 108
T
5 K−5 s−1 of the driving-field frequency have been obtained, at which the above effect can be observed. In particular, E
⊥ ≃ 1 kV/cm corresponds to T ≲ 70 mK and ω/2π ≲ 30 Hz. 相似文献
14.
N Venkataramani K Muralfedharan A Datta S N Bhatia OM Prakash C M Srivastava 《Pramana》1988,30(5):L455-L457
Zr and Ti have been substituted in the system Y1−x
M
x
Ba2Cu3O7−δ(M=Zr, Ti,x=0.05,0.1). We find that theT
c value is unchanged, ∼90K for Zr substitutions up to 10% and in the case of Ti substitutions theT
c drops significantly. These changes may arise from their site preference. 相似文献
15.
Y. J. Uemura L. P. Le G. M. Luke B. J. Sternlieb J. H. Brewer J. Carolan W. Hardy R. Kadono R. F. Kiefl S. R. Kreitzman T. M. Riseman C. L. Seaman J. J. Neumeier M. B. Maple G. Saito H. Yamochi H. Takagi S. Uchida J. Gopalakrishnan M. A. Subramanian A. W. Sleight Gang Xiao 《Hyperfine Interactions》1991,63(1-4):131-137
We update our muon spin relaxation studies of the magnetic field penetration depth which show the correlations betweenT
c and the relaxation rate σ αn
s/m
* (carrier density/effective mass) of hole-doped high-T
c cuprate superconductors (La2, Sr3)CuO4, YBa2Cu3O7 (Y1−xPrx)Ba2Cu3O7, and other double and triple layer systems. These studies are extended to the organic superconductor (BEDT-TTF)2Cu(NCS)2. 相似文献
16.
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
17.
The heavy-fermion metal CePd1−x
Rh
x
can be tuned from ferromagnetism at x = 0 to the nonmagnetic state at some critical concentration x
c
. The non-Fermi liquid behavior (NFL) at x ≃ x
c
is recognized by the power-law dependence of the specific heat C(T) given by the electronic contribution susceptibility X(T) and volume expansion coefficient α(T) at low temperatures: C/T ∝ X(T) ∝ α(T)/T∝ 1/ √T. We also demonstrate that the behavior of the normalized effective mass M
N
*
observed in CePd1−x
Rh
x
at x ≃ 0.8 agrees with that of M
N
*
observed in paramagnetic CeRu2Si2 and conclude that these alloys exhibit the universal NFL thermodynamic behavior at their quantum critical points. We show
that the NFL behavior of CePd1−x
Rh
x
can be accounted for within the frameworks of the quasiparticle picture and fermion condensation quantum phase transition,
while this alloy exhibits a universal thermodynamic NFL behavior that is independent of the characteristic features of the
given alloy such as its lattice structure, magnetic ground state, dimension, etc.
The text was submitted by the authors in English. 相似文献
18.
A. T. Burkov 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(10):1392-1394
Results on the experimentally investigated dependence of the electrical resistivity of quasibinary alloys R
x
Y1−x
Co2, where R stands for magnetic rare earth elements, on temperature (2–300 K), composition (x = 0–1), and magnetic field (0–15 T) are presented. Non-Fermi liquid behavior of electrical resistivity in a magnetic field
was observed in paramagnetic Gd
x
Y1−x
Co2 alloys. The relative magneto-thermopower of these alloys exhibits diverging behavior with decreasing temperature, indicating
anomalous temperature variation of the thermopower in the non-Fermi liquid regime. 相似文献
19.
O. Yu. Gorbenko R. V. Demin A. R. Kaul’ L. I. Koroleva R. Szymczak 《Physics of the Solid State》1998,40(2):263-267
A study is reported of the magnetic, electrical, and crystallographic properties of La1−x
SrxMnO3 (0.15⩽x⩽0.23) epitaxial films grown on single-crystal substrates of (001)ZrO2(Y2O3) having the fluorite structure and (001)LaAlO3 having the perovskite structure. It was found that films with close compositions for x=0.15 and 0.16, grown on different substrates, have different properties, namely, the film on a fluorite substrate is semiconducting
and has a coercive strength 30 times that of the film on a perovskite substrate; the temperature dependence of electrical
resistance of the latter film has a maximum around the Curie point T
C and follows metallic behavior for T<T
C. These differences are explained as due to different structures of the films. The x=0.23 film on the perovskite substrate has been found to exhibit a combination of giant magnetoresistance at room temperature
with a resistance of ≈300 Ω which is useful for applications. The maxima in resistance and absolute value of negative magnetoresistance
are accounted for by the existence of two-phase magnetic states in these films.
Fiz. Tverd. Tela (St. Petersburg) 40, 290–294 (February 1998) 相似文献
20.
Magnetic and thermal properties of CuFeS<Subscript>2</Subscript> at low temperatures 总被引:1,自引:0,他引:1
The magnetic moment M, the magnetic susceptibility χ, and the thermal conductivity of chalcopyrite CuFeS2, which is a zero-gap semiconductor with antiferromagnetic ordering, have been measured in the temperature range 10–310 K.
It has been revealed that the quantities χ(T) and M(T) increase anomalously strongly at temperatures below ∼100 K. The temperature dependence M(T) is affected by the magnetic prehistory of the sample. An analysis has demonstrated that the magnetic anomalies are associated
with the presence of a system of noninteracting magnetic clusters in the CuFeS2 sample under investigation. The formation of the clusters is most likely caused by the disturbance of the ordered arrangement
of Fe and Cu atoms in the metal sublattice of the chalcopyrite, which is also responsible for the phase inhomogeneity of the
crystal lattice. The inhomogeneity brings about strong phonon scattering, and, as a result, the temperature dependence of
the thermal conductivity coefficient exhibits a behavior characteristic of partially disordered crystals. 相似文献