Quantum Criticality in YbCu4Ni

We report on the quantum criticality of YbCu$_4$Ni as revealed by our combined micro- and macro-measurements. We determine the crystal structure of YbCu$_4$Ni with site mixing by neutron diffraction measurements, which suggests the possible presence of Kondo disorder. However, decreasing the local spin susceptibility distribution and the development of spin fluctuations below 10 K at ambient pressure by muon spin rotation and relaxation measurements suggests that YbCu4Ni exhibits quantum criticality. Therefore, our experimental results indicate that YbCu4Ni is a new material that exhibits quantum criticality under a zero magnetic field and ambient pressure.
Comment: 8 pages, 5 figures