共查询到20条相似文献,搜索用时 15 毫秒
1.
N.B. Brandt V.V. Moshchalkov N.E. Sluchanko E.M. Savitskii T.M. Shkatova 《Solid State Communications》1985,53(8):645-648
We have studied temperature dependences of the Hall coefficient RH(T) and resistivity ?(T) in substitutional solid solutions CexLa1?xAl3 (0 ≤ x ≤ 1) which realize the transition from Kondo impurity regime (X?1) to Kondo lattice (X = 1). Lowering temperature results in the anomalous increase of RH(T). The ratio r = RH(3 K)/RH(100 K) has been found to increase with cerium content up to the r ? 15 in the marginal compound CeAl3. The specific features of RH(T) behaviour in CexLa1?xAl3 alloys seem to be related to the existence at low temperatures of heavy fermions due to the formation of the narrow Abrikosov-Suhl resonance at the Fermi level. 相似文献
2.
研究了Ce填充分数对富Co组成的填充式skutterudite化合物:CeyFe1.5 sub>Co2.5Sb12(y=0—0.46)的热电传输特性的影响.CeyFe1.5Co2.5Sb12有现为p型传导.霍尔系数RH sub>随Ce填充分数的增加而增加,空穴浓度p和电导率σ随Ce填充分数的增加而减少.泽贝克 系数α随Ce填
关键词:
填充分数
载流子浓度
电导率
泽贝克系数
晶格热导率 相似文献
3.
N. E. Sluchanko A. V. Bogach V. V. Glushkov S. V. Demishev N. A. Samarin G. S. Burkhanov O. D. Chistyakov 《JETP Letters》2002,76(1):26-29
The Hall coefficient R H and magnetoresistance of a magnetic Kondo lattice of CeAl2 were investigated over a wide temperature range from 1.8 to 300 K in magnetic fields of up to 80 kOe. Analysis of the measured angular dependences R H(?, T, H) made it possible to separate the contributions of skew scattering and anomalous magnetic scattering to the anomalous Hall effect. The results obtained were compared with the existing theoretical models. 相似文献
4.
S.C. Schneider M. Levy R. Chen M. Tachiki D.C. Johnston B.T. Matthias 《Solid State Communications》1981,40(1):61-64
The attenuation coefficient of longitudinal sound waves propagating in ErRh4B4 has been measured as a function of applied magnetic field where the propagation direction (q) of the sound waves was oriented either parallel or perpendicular to Happlied. For both orientations there is evidence of a type II-1 superconducting transition at Hc1 for T ≈ 1.5 K. In addition, when q ⊥ H an increase in attenuation is evident at Hc2, which does not appear when q 6 H, consistent with theories developed by Tachiki et al. utilizing supercurrent screening of the internal magnetic fields. 相似文献
5.
A. V. Bogach G. S. Burkhanov V. V. Glushkov S. V. Demishev O. D. Chistyakov N. E. Sluchanko 《Journal of Experimental and Theoretical Physics》2007,105(1):108-111
The influence of substitution on the binding energy of many-body states and the formation of the magnetically ordered state in a heavy-fermion compound (CeAl2) have been studied by measuring the transport characteristics (Hall effect, resistivity) in intermetallic compounds of the Ce(Al1?x M x )2 system (M = Ni, Co; x ≤ 0.08). It is established that the Hall coefficient R H in Ce(Al1?x Co x )2 intermetallides with x = 0.05 and 0.08 grows by more than an order of magnitude as the temperature decreases from 1.8 to 300 K. The experimental data are used to estimate the effective mass of charge carriers, the relaxation time, and the localization radius of many-body states. 相似文献
6.
In single crystals of Bi with resistivity ratio R293/R4.2 ≈ 300 by a helium temperature at frequencies 500 MHz of longitudinal sonic wave detected and investigated the longitudinal acoustoelectric effect.In strong magnetic fields if the condition Ω ? kT,ql ? 1 Ω — cyclotron frequency, k — Boltzman constant) for directions H 6 q 6 y (y— a bissector crystal axis) and H 6 q 6 z (z — a triagonal crystal axis) is fulfilled, giant quantum oscillations of longitudinal acoustoelectric current are detected. Sign of current oscillations is determined by the type of current carriers. 相似文献
7.
用熔融法合成了单相填充式skutterudite化合物CeyFexCo4-x Sb12(x=0—3.0,y=0—0.74).对Ce的填充范围,置换Fe原子对化合物的结 构及热电传输特性的影响进行了研究,Ce的填充分数随Fe含量的增加而线性增加,当Fe含量 大约为3时,Ce的填充分数达到0.74.晶格常量a随Fe含量的增加而增加,Ce的填充使晶格常 量进一步增加.当Ce填充分数达到饱和状态时,Cey
关键词:
填充式skutterudite化合物
晶体结构
热电传输性质 相似文献
8.
The information theoretic surprisal analysis is employed to characterise the recent quantal close-coupling computations of rotational excitation rates by Green. The analysis is based on comparing the actual rates to the priors k0 which depend only on the temperature and the reduced “energy defect” ΔER/kT. The surprisal representation of the computed rates as k=k0 x exp (-I0 - θR6ΔER6/kT is accurate throughout the temperature range considered by Green and is found to reduce in the low and high temperature limits to functional forms previously employed to characterise the rotational energy transfer rates in H2. 相似文献
9.
J.M. DonallyM. Cutler 《Journal of Physics and Chemistry of Solids》1972,33(5):1017-1022
The proper interpretation of the Hall coefficient RH of liquid semiconductors is still an unsolved problem, and it is a particularly interesting one in view of the frequently observed discrepancy in sign with the Seebeck coefficient. We present some new data which include measurements of the Hall mobility μH in liquid thallium-tellurium through the composition range where the Seebeck coefficient S changes sign, and in the range where S is negative. An abrupt change in magnitude of μH occurs at the intrinsic composition (Tl2Te, where S changes sign), and μH is observed to have an appreciable dependence on temperature only at this composition. This is consistent with transport by carriers in two bands. μH is lower on the Tl-rich side of Tl2Te, and the formula nH = 1/RHe yields a value for nH which is ten times larger than the electron concentration inferred from the composition, assuming that electrons are derived from the Tl in excess of Tl2Te. We review the various suggested interpretations of the Hall effect in liquid semiconductors from several points of view, and conclude that the conventional formula n = ± 1/RHe is unreliable for inferring either the sign or concentration of the carriers. 相似文献
10.
The transport coefficients of tellurium-doped n-Bi1 ? x Sb x semiconducting alloys (0.07 ≤ x ≤ 0.15) are studied for single-crystal samples in the temperature range 1.5 ≤ T ≤ 40 K and in magnetic fields 0 ≤ H < 20 kOe. The theory developed in this study attributes the specific features in the behavior of the transport coefficients observed in a magnetic field to a strong anisotropy of the electron spectrum and anisotropy in the electron relaxation time. It is found that the dependences of the transport coefficients on the magnetic field for H ∥ C 3 can be theoretically expressed through one anisotropy parameter δ, and those for H ∥ C 2, by means of several anisotropy parameters, namely, γ, η, ζ, and m 3/m 1. It is established that the anisotropy parameter δ in the n-Bi-Sb semiconducting alloys can be estimated from measurements of the electrical resistivity ρ22(∞)/ρ22(0) ? δ and the Hall coefficient R 12.3(∞)/R 12.3(H → 0) ? δ in a magnetic field H ∥ C 3. It is shown that the observed increase in the thermoelectric efficiency by a factor of 1.5–2.0 in the transverse magnetic fields H ∥ C 3 and H ∥ C 2 originates from the nonmonotonic dependence of the diffusion component of the thermopower Δα22(H)(?T ∥ C 1) on the magnetic field. The nonmonotonic dependence of the diffusion thermopower in n-Bi-Sb semiconducting alloys is associated with the strong anisotropy of the electron spectrum, the anisotropy in the electron relaxation time, and the many-valley pattern of the spectrum. 相似文献
11.
N. E. Sluchanko A. V. Bogach V. V. Glushkov S. V. Demishev M. I. Ignatov N. A. Samarin G. S. Burkhanov O. D. Chistyakov 《Journal of Experimental and Theoretical Physics》2004,98(4):793-810
The Hall coefficient R H , resistivity ρ, and Seebeck coefficient S of the CeAl2 compound with fast electron density fluctuations were studied in a wide temperature range (from 1.8 to 300 K). Detailed measurements of the angular dependences R H (? T, H≤70 kOe) were performed to determine contributions to the anomalous Hall effect and study the behavior of the anomalous magnetic R H am and main R H a components of the Hall signal of this compound with strong electron correlation. The special features of the behavior of the anomalous magnetic component R H am were used to analyze the complex magnetic phase diagram H-T determined by magnetic ordering in the presence of strong spin fluctuations. An analysis of changes in the main contribution R H a (H, T) to the Hall effect made it possible to determine the complex activation behavior of this anomalous component in the CeAl2 intermetallic compound. The results led us to conclude that taking into account spin-polaron effects was necessary and that the Kondo lattice and skew-scattering models were of very limited applicability as methods for describing the low-temperature transport of charge carriers in cerium-based intermetallic compounds. The effective masses and localization radii of manybody states in the CeAl2 matrix were estimated to be (55–90)m0 and 6–10 Å, respectively. The behaviors of the parameters R H , S, and ρ were jointly analyzed. The results allowed us to consistently describe the transport coefficients of CeAl2. 相似文献
12.
C. Ghezzi 《Solid State Communications》2004,130(10):647-652
Magnetoquantum oscillations of the Hall coefficient RH were observed in Te-doped GaSb layers grown by molecular beam epitaxy. The free electron densities were in the low 1016 cm−3 range or even slightly lower, thus achieving, for the first time in GaSb, the extreme quantum limit, where all the electrons occupy the spin-split 0(+) Landau level (LL). Similarly to other known cases, the amplitude of the last maximum of RH could be explained as enhanced by the metal-to-insulator transition of the spin-down electron system in the n=0 LL. The occurrence of the last negative oscillation of RH below its classical value, called Hall dip, could be frustrated, in samples with sufficiently low carrier densities, by an incipient carrier freeze-out at donor impurities induced by the magnetic field. 相似文献
13.
I.M. Vardavas 《Journal of Quantitative Spectroscopy & Radiative Transfer》1976,16(8):715-719
The effects of frequency and angular redistribution on line formation are examined in static isothermal atmospheres for scattering described by the redistribution function RIII(x′, n′; x, n). For an optically thin atmosphere, it is found that the emergent line intensities obtained using RIII are essentially the same as RI and RII. In the case of a semi-infinite atmosphere, the emergent line intensities obtained using RIII, whether angle-averaged or angle-dependent, did not differ substantially from the complete redistribution results. 相似文献
14.
在大量的非过渡金属和合金中,非晶态超导体的能隙2△0与霍耳系数R_H以及与相应的液态金属霍耳系数RHL之间存在着一个经验关系:在RH(或RHL)=-3.5—-4.0×10-11m3/AS之间出现一个2△0最大值。
关键词: 相似文献
15.
A. M. Belemuka A. F. Barabanov L. A. Maksimov 《Journal of Experimental and Theoretical Physics》2006,102(3):431-443
Temperature dependences of resistivity, ρ(T), and Hall coefficient, R H (T), in a 2D doped antiferromagnet are studied for various forms of the dynamic spin susceptibility X(q, θ) (in the mean-field approximation, taking into account attenuation and renormalization of the magnetic excitation spectrum θq, and for so-called strongly overdamped magnons). Doped CuO2 planes in cuprates are considered in the one-band model of the Kondo lattice. Charge carrier scattering anisotropy, which strongly depends on temperature, is taken into account using the density matrix formalism and seven-moment approximation for the nonequilibrium distribution function. It is shown that the behavior of ρ(T) and R H (T) is completely determined by the renormalization θq → $\omega _q \to \tilde \omega _q $ of the spin wave spectrum (the renormalization is essentially controlled by the fulfillment of the sum rule for X(q, θ) and by the strong temperature dependence of the gap δ(T). The resultant ρ(T) and R H (T) dependences match the experimental data for optimally doped high-T c superconductors. 相似文献
16.
A. I. Kokorin E. N. Golubeva B. Y. Mladenova V. A. Tran T. Kálai K. Hideg G. Grampp 《Applied magnetic resonance》2013,44(9):1041-1051
Intramolecular electron spin exchange (IESE) in two nitroxide biradicals, R6–C≡C–C≡C–R6 (1) and R6–C≡C–p-C6H4–C≡C–R6 (2), is studied as a function of temperature and solvent properties. The effect of molecular solvents and ionic liquids (ILs, [1-methyl-3-butylimidazolium]+[PF6]?, bmimPF6, and [1-methyl-3-octylimidazolium]+[BF4]?, omimBF4) on the IESE in magnetically diluted solutions is investigated. Changes in electron paramagnetic resonance spectra are analyzed and the thermodynamic parameters of these changes are calculated. Geometry optimization and D-tensor calculations of biradicals 1 and 2 were carried out on the DFT/UB3LYP/cc-pVdz and DFT/ROPBE/N07D levels of theory. The probable differences in biradical behavior are discussed. 相似文献
17.
We present the result of our accurate measurements of the a- and b-axis resistivity (ρa and ρb), magnetoconductivity Δσ/σ, Hall coefficient RH, and the a-axis thermopower Sa in untwinned YBa2Cu3Oy single crystals in a wide range of doping (6.45≤y≤7.0). The systematics of our data reveals a number of novel 60-K-phase anomalies in the charge transport: (i) temperature dependences of ρa show anomalous overlap below ∼130 K for 6.65≤y≤6.80, (ii) Hall mobility μH shows an enhancement near y?6.65, which is reflected in an anomalous y dependence of σxy, (iii) with decreasing temperature RH shows a marked drop upon approaching Tc only in samples with 6.70≤y≤6.85, (iv) superconducting fluctuation magnetoconductivity is anomalously enhanced near y?6.7, and (v) Hc2 is anomalously reduced near y?6.70. We discuss that the fluctuating charge stripes might be responsible for these anomalies in the charge transport. 相似文献
18.
19.
K. Winzer 《Solid State Communications》1977,24(8):551-556
The dependence of the superconducting transition temperature Tc on Ce impurity concentration is reported for the (La0.80Y0.20)Ce system. Susceptibility and resistivity measurements on samples with about 0.85 at. % Ce show unique behavior which must be interpreted as a superposition of three transition curves: a first transition at 0.55 K from the normal to the superconducting state, a second one at 0.27 K back to the normal state, and finally a third one at about 0.05 K again to the superconducting state. The experimental evidence of this third transition (Tc3) is of special importance for the decision about the relevant physical mechanism of pair-breaking at low temperature (T ? TK). 相似文献
20.
Using a novel modification of the standard crossed-coil helicon method, we have investigated the temperature dependence of the Hall coefficient, RH, of the metal-ammonia compound lithium tetra-ammine, Li(NH3)4. When cooling from 77 K, there is a discontinuous change in RH of 25 per cent near 64 K. This may be evidence of a new low temperature phase. 相似文献