Divergence of the Magnetic Gruneisen Ratio at the Field-Induced Quantum Critical Point in YbRh2Si2

作者：Tokiwa Y^*; Radu T; Geibel C; Steglich F; Gegenwart P

来源：Physical Review Letters, 2009, 102(6): 066401.

DOI：10.1103/PhysRevLett.102.066401

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.

• 出版日期2009-2-13