共查询到19条相似文献,搜索用时 171 毫秒
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测量了重电子金属CeCu6-xNix(x=0,005,01,015,02)01K—250K的低温电阻和5K—70K低温比热,发现样品电阻的极大值温度随着掺Ni含量的增大而急剧下降,这一现象反映少数与Ni邻近的Ce离子在极低温下磁矩的加强和整个Ce离子点阵对导电电子相干散射的减弱.与此相反,低温电子比热系数γ在较低温度下近于常数,而在8K附近因有效质量变大而明显上升,但γ明显上升的温度,对Ni的含量却不敏感,表明绝大部分Ce离子的状况并未受到影响
关键词:
重费米子系统
低温比热
低温电阻 相似文献
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介绍了重电子金属CeCu6-xCdx(x=0.10,0.15,0.20,0.30,0.50)在1.8-300K温度范围内,在磁场(μ0H=0,5,10T)下电阻随温度的变化规律及低温(1.9,15 K)下的磁电阻(μ0H=0-10T).实验表明所有样品在零场下的Tmax(对应于电阻极大值的温度)都低于1.8 K.加磁场后,Tmax随磁场和掺杂量x的增加明显向高温方向变化.此外,各样品的磁电阻在1.9 K全是负值,温度升高到15 K以后,磁电阻有变为正值的趋势.从近藤散射和相干散射的角度对这一现象的物理机制进行了分析. 相似文献
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本文基于Andersonsd混合作用和sd交换作用,利用Green函数方法,定量地研究了磁性杂质效应在充分低的温度下,对稀磁合金中低温电阻和热导率的影响.由此得知,sd混合效应和sd交换效应所引起的电阻按温度的平方律减小,且sd交换效应所引起的低温电阻随温度的平方律减小的更快,同时热导率随温度的升高而变大. 相似文献
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采用溶胶-凝胶法制备了系列多晶CMR材料La2/3(Cao 60Bao.40)1/3Mn1-xVXO3,(x:0%、1%、5%、7%、10%、15%、20%).在零场下、77~350 K温度范围内测量了其电阻率随温度的变化关系,测量了该温度范围内0.1 T磁场下磁化强度随温度的变化关系.采用小极化子绝热跃迁模型P=aTexp(E/kT)对样品的电导特性进行拟合研究.结果发现,高温区电阻率随温度的变化很好地满足小极化子绝热跃迁模型;同时,采用单磁子散射模型对样品低温区的电输运曲线进行拟合,结果发现所有样品低温区的p~T关系同样都很好地满足单磁子散射公式P=po AT2严.由拟合结果分析了样品高温区的输运行为主要来源于小极化子的影响,而低温区电导特性主要来源于单磁子散射. 相似文献
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Tsujii H Tanaka E Ode Y Katoh T Mamiya T Araki S Settai R Onuki Y 《Physical review letters》2000,84(23):5407-5410
We have measured the ac magnetic susceptibility in various fields and thermal expansion of single crystals of the heavy fermion compound CeCu6 at temperatures down to 250 &mgr;K. The susceptibility of CeCu6 shows a peak at about 2 mK and has a large anisotropy. We also detected an anomaly of thermal expansion at the same temperature. The observed behaviors of the susceptibility and the thermal expansion in CeCu6 indicate the occurrence of an antiferromagnetic order. 相似文献
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In the archetypal strongly correlated electron superconductor CeCu2Si2 and its Ge-substituted alloys CeCu2(Si1-xGex)2 two quantum phase transitions--one magnetic and one of so far unknown origin-can be crossed as a function of pressure. We examine the associated anomalous normal state by detailed measurements of the low temperature resistivity (rho) power-law exponent alpha. At the lower critical point (at pcl, 1相似文献
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Silhanek AV Ebihara T Harrison N Jaime M Tezuka K Fanelli V Batista CD 《Physical review letters》2006,96(20):206401
We show that antiferromagnetism in lightly (approximately 8%) Sn-doped CeIn3 terminates at a critical field mu0H(c) = 42 +/- 2 T. Electrical transport and thermodynamic measurements reveal the effective mass m* not to diverge, suggesting that cubic CeIn3 is representative of a critical spin-density wave (SDW) scenario, unlike the local quantum critical points reported in anisotropic systems such as CeCu(6-x)Au(x) and YbRh2Si(2-x)Ge(x). The existence of a maximum in m* at a lower field mu0H(x) = 30 +/- 1 T may be interpreted as a field-induced crossover from local moment to SDW behavior as the Néel temperature falls below the Fermi temperature. 相似文献
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We report an inelastic neutron-scattering study at the field-induced magnetic quantum phase transition of CeCu5.8Au0.2. The data can be described better by the spin-density-wave scenario than by a local quantum critical point, while the latter scenario was shown to be applicable to the zero-field concentration-tuned quantum phase transition in CeCu6-xAux for x=0.1. This constitutes direct microscopic evidence for a difference in the quantum fluctuation spectra at a magnetic quantum critical point driven by different tuning parameters. 相似文献
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采用溶胶 凝胶自燃烧法制备了纳米尺度的锌钴铁氧体Zn06CoxFe24- xO4(x=0—030)粉体,分别在不同温度下进行了热处理,利用x射线衍射仪(XRD) 和振动样品磁强计(VSM)对其物 相结构和磁性进行了测量和分析.实验结果表明,锌钴铁氧体Zn06Co015Fe 225O4在550—800℃温度区间出现α Fe2O3过渡相,在高于800℃温度时生 成 单一尖晶石相锌钴铁氧体;随钴含量的增加,Zn06CoxFe2
关键词:
锌钴铁氧体
磁性
结构
相变
溶胶 凝胶 相似文献
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用共沉淀法制备了结构式为Ni1-xZnxFe2O4 (x=0.0,0.1,0.2,0.3,0.4,0.5,0.6,0.7)的铁酸盐纳米颗粒,并对这些纳米颗粒进行了X射线衍射,磁化和交流易感性的测量.X射线衍射的分析结果确认了样品中形成的单相结构.从X射线衍射谱获得的晶格参数随锌的配比x的增大而增大.通过X射线衍射强度比的计算获得了阳离子分布.磁化研究的结果表明在x<0.4时亚铁磁结构与磁性有共线性关系,而x>0.4时没有共线性关系.交流易感性测量获得的居里温度TC被发现随x的升高而降低. 相似文献
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We report on the magnetic ac/dc susceptibility and specific heat measurements for the CeCu(4)Mn(y)Al(1-y) series of compounds with 0 ≤ y ≤ 1. All compounds investigated crystallize in the hexagonal CaCu(5)-type structure with the space group P6/mmm. The results reveal that the frustration of the interactions dominates and leads to a spin-glass (SG) behaviour with a linear change of the freezing temperature T(f) as a function of y. The SG state has been confirmed by the frequency dependence of the ac magnetic susceptibility, the relaxation of the remanent magnetization and the split of the field-cooled-zero-field-cooled dc magnetic susceptibility. The electronic specific heat coefficient γ is enhanced for all y and increases with the Al content. Below a threshold at y ≈ 0.3, γ is large even if determined for temperatures above T(f); moreover the paramagnetic Curie-Weiss temperature θ(p) changes sign to negative. These observations indicate the possible presence of the heavy fermion (HF) state, at least below y ≈ 0.3, and the possible coexistence of the SG and HF states down to y = 0, i.e. for the CeCu(4)Al compound. A tentative magnetic phase diagram for CeCu(4)Mn(y)Al(1-y) has been constructed. 相似文献