Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan 277-8581.
Phys Rev Lett. 2012 Oct 26;109(17):176405. doi: 10.1103/PhysRevLett.109.176405.
β-YbAlB(4) is the unique heavy fermion superconductor that exhibits unconventional quantum criticality without tuning in a strongly intermediate valence state. Despite the large coherence temperature, set by the peak of the longitudinal resistivity, our Hall effect measurements reveal that resonant skew scattering from incoherent local moments persists down to at least ~40 K, where the Hall coefficient exhibits a distinct minimum signaling another formation of coherence. The observation strongly suggests that the hybridization between f moments and conduction electrons has a two-component character with distinct Kondo or coherence scales T(K) of ~40 K and 200 K; this is confirmed by the magnetic field dependence of ρ(xy).
β-YbAlB(4) 是唯一的重费米子超导体，在没有强中间价态调谐的情况下表现出非常规量子临界点。尽管由纵向电阻率峰值设定的相干温度很大，但我们的霍尔效应测量表明，来自非相干局域磁矩的共振倾斜散射至少持续到 40 K，此时霍尔系数表现出明显的最小值，表明另一种相干性的形成。这一观察结果强烈表明，f 磁矩和传导电子之间的杂化具有双分量特征，其 Kondo 或相干标度 T(K)分别为40 K 和 200 K；这一点通过 ρ(xy)对磁场的依赖关系得到了证实。
