Divergence of the Magnetic Gruneisen Ratio at the Field-Induced Quantum Critical Point in YbRh2Si2
Divergence of the Magnetic Gruneisen Ratio at the Field-Induced Quantum Critical Point in YbRh2Si2
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DOI：
10.1103/physrevlett.102.066401
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发表时间：
2009-02-13
影响因子：
8.6
通讯作者：
Gegenwart, P.
中科院分区：
文献类型：
--
作者：
Tokiwa, Y.;Radu, T.;Gegenwart, P.
通过在接近量子临界点（H-c=0.06 T，H 垂直于 c）的磁场下的低温磁化强度 M(T) 和比热 C(T) 测量研究了重费米子金属 YbRh2Si2。在接近不稳定状态时，dM/dT 比 C(T) 更奇异，导致磁格鲁尼森比 Gamma(mag)=-(dM/dT)/C 发散。在费米液体范围内，Gamma(mag)=-G(r)(H-H-c(fit))，其中 G(r)=-0.30 +/- 0.01 且 H-c(fit)=(0.065 +/- 0.005) T，这与 YbRh2(Si0.95Ge0.05)(2) 中比热系数的标度行为一致。 dM/dT 的场依赖性表明，熵在经过先前在霍尔和热力学测量中观察到的线 T-star(H) 时作为磁场的函数的拐点。
The heavy-fermion metal YbRh2Si2 is studied by low-temperature magnetization M(T) and specific-heat C(T) measurements at magnetic fields close to the quantum critical point (H-c=0.06 T, H perpendicular to c). Upon approaching the instability, dM/dT is more singular than C(T), leading to a divergence of the magnetic Gruneisen ratio Gamma(mag)=-(dM/dT)/C. Within the Fermi-liquid regime, Gamma(mag)=-G(r)(H-H-c(fit)) with G(r)=-0.30 +/- 0.01 and H-c(fit)=(0.065 +/- 0.005) T which is consistent with scaling behavior of the specific-heat coefficient in YbRh2(Si0.95Ge0.05)(2). The field dependence of dM/dT indicates an inflection point of the entropy as a function of magnetic field upon passing the line T-star(H) previously observed in Hall and thermodynamic measurements.