Physical Properties of Novel 4f electrons in ytterbium-based compounds

为了研究低温比热大的Yb基化合物的电子态，我们对半赫斯勒化合物YbPtSb进行了NMR测量。研究了高温下局域4f自旋的特性。我们发现在10 K附近动态电子性质发生了变化，这是作为核自旋-晶格弛豫速率和核自旋-自旋弛豫速率的异常而观察到的。然而，在静态特性中检测到任何异常，例如奈特位移和比热。这种异常的低温状态可能与在0.4K以下的磁有序态中观察到的小磁矩的形成有关。

In order to investigate an electronic state in Yb-based compounds with large low-temperature specific heat, we performed NMR measurement in the half-Heusler compound YbPtSb. The characteristics of localized 4f spins were observedat high temperatures. We found that the dynamicalelectronic properties change at around 10 K, which were observed as anomalies in the nuclear spin-lattice relaxation rate and the nuclear spin-spin relaxation rate. However, any anomalies were detected in static properties such as Knight shift and a specific heat. This unusual low-temperature state may be associated with the formation of the small magnetic moment which observed in the magnetically ordered state below 0.4 K.