Valenta J, Tsujii N, Yamaoka H, Honda F, Hirose Y, Sakurai H, Terada N, Naka T, Nakane T, Koizumi T, Ishii H, Hiraoka N, Mori T
International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan.
RIKEN Spring-8 Center, Sayo, Hyogo 679-5148, Japan.
J Phys Condens Matter. 2023 Apr 20;35(28). doi: 10.1088/1361-648X/acca5a.
We report the first study of electrical resistivity, magnetization, and specific heat on YbCo. The measurements on a single-phased sample of YbCobring no evidence of magnetic ordering down to 0.3 K in a zero magnetic field. The manifestations of low Kondo temperature are observed. The specific heat value divided by temperature,, keeps increasing logarithmically beyond 7 J/mol Kwith decreasing temperature down to 0.3 K without no sign of magnetic ordering, suggesting a very large electronic specific heat. Analysis of the magnetic specific heat indicates that the large portion of the low-temperature specific heat is not explained simply by the low Kondo temperature but is due to the strong intersite magnetic correlation in both the 3and 4electrons. Temperature-dependent measurements under static magnetic fields up to 7 T are carried out, which show the evolution of field-induced transition above 2 T. The transition temperature increases with increasing field, pointing to a ferromagnetic character. The extrapolation of the transition temperature to zero field suggests that YbCois in the very proximity of the quantum critical point. These results indicate that in the unique case of YbCo, the itinerant electron magnetism of Co 3-electrons and the Kondo effect within the vicinity of quantum criticality of Yb 4-local moments can both play a role.
我们报告了关于YbCo的电阻率、磁化强度和比热的首次研究。在零磁场下，对YbCo单相样品进行测量，直至0.3 K均未发现磁有序的证据。观察到了低近藤温度的表现。比热值除以温度，在温度降至0.3 K时，超过7 J/mol K后随温度降低呈对数增加，且无磁有序迹象，表明存在非常大的电子比热。对磁比热的分析表明，低温比热的很大一部分不能简单地用低近藤温度来解释，而是由于3d和4f电子中强烈的位点间磁关联。进行了高达7 T静磁场下的温度相关测量，结果显示在2 T以上场致转变的演变。转变温度随磁场增加而升高，表明具有铁磁特性。将转变温度外推至零场表明YbCo非常接近量子临界点。这些结果表明，在YbCo这种独特的情况下，Co 3d电子的巡游电子磁性和Yb 4f局域磁矩量子临界附近的近藤效应都可能起作用。
