PROPERTIES OF YBAGCU4 AT HIGH-PRESSURES AND MAGNETIC-FIELDS
PROPERTIES OF YBAGCU4 AT HIGH-PRESSURES AND MAGNETIC-FIELDS
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DOI：
10.1103/physrevb.52.3099
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发表时间：
1995-08-01
影响因子：
3.7
通讯作者：
CANFIELD, PC
中科院分区：
文献类型：
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作者：
GRAF, T;MOVSHOVICH, R;CANFIELD, PC
我们测量了YbAgCu_4在190 kbar准流体静压和8 T磁场下的电阻率。在环境压力下，YbAgCu 4是弱混合价，并且具有大约240 mJ/mole K-2的比热γ的索末菲系数。随着施加的压力，基态简并度从八倍减少到两倍简并，因为表征强相关电子系统的能量标度T-0从130减少到类似于190千巴下的0.9 K，并且伽马估计增加到约4900 mJ/mole K-2。在中等压力下，T-0和晶场分裂是相当的，这说明了在这些压力下缺乏电阻缩放。系统的压力依赖性电阻率表明，YbAgCu 4应磁秩序在压力不远高于190千巴。由于晶格缺陷对重准粒子的共振散射，YbAgCu 4的“剩余磁导率”rho（0）随着体积的减小而显著增加。在高压和低温下的磁阻是大的和负的，并具有预期的自旋1/2近藤杂质的场依赖性。ρ（0）和电阻率T-2系数的压力和场依赖性提出了它们之间的函数关系问题，以及我们如何理解强关联准粒子带中的类杂质行为。
We have measured the electrical resistivity of YbAgCu4 at quasihydrostatic pressures to 190 kbar and in magnetic fields to 8 T. At ambient pressure, YbAgCu4 is weakly mixed valent and has a Sommerfeld coefficient of specific heat gamma of approximately 240 mJ/mole K-2. With applied pressure, the ground-state degeneracy is reduced from eightfold to twofold degenerate as the energy scale T-0 characterizing the strongly correlated electron system is reduced from 130 to similar to 0.9 K at 190 kbar and gamma is estimated to increase to approximately 4900 mJ/mole K-2. At intermediate pressures T-0 and crystal-field splittings are comparable, which accounts for the lack of resistive scaling at these pressures. Systematics in the pressure-dependent resistivity suggest that YbAgCu4 should order magnetically at pressures not far above 190 kbar. The ''residual resistivity'' rho(0) of YbAgCu4 increases dramatically with decreasing volume due to resonant scattering of heavy quasiparticles by lattice defects. At high pressures and low temperatures the magnetoresistance is large and negative and has the field dependence expected of a spin-1/2 Kondo impurity. The pressure and field dependences of rho(0) and the T-2 coefficient of resistivity raise the question of their functional relationship and how we are to understand impuritylike behavior in a band of strongly correlated quasiparticles.