Investigation of anomalous ground state on geometrically frustrated magnet

烧绿石氧化物Tb_2Ti_2O_7没有表现出任何低至20mK的长程有序性，并且真正的基态尚未建立。最近，理论家提出，在这种材料的基态下，实现了“量子自旋冰”态。该状态由通过第一激发双峰杂交的六个经典自旋冰状态的叠加组成。从沿[100]、[110]、[111]方向的磁场中直流磁化强度和比热测量到100 mK，我们阐明了类伊辛磁各向异性，并且在0.5K以下观察到类似于自旋冰化合物的Kagome平台的平台状特征。此外，我们观察到比热的异常，表明相变到量子自旋冰态。

Pyrochlore oxide Tb_2Ti_2O_7 dose not show any long range ordering down to 20mK and the true ground state had not established yet. Recently, theorists proposed that in the ground state of this material the "quantum spin ice" state is realized. This state consists of the superposition of six classical spin ice states by the hybridization of first excited doublet. From the DC magnetization and specific heat measurements down to 100 mK in the magnetic field along [100], [110], [111] directions, we clarified the Ising-like magnetic anisotropy and the plateau-like feature is observed below 0.5K similar to the Kagome-plateau of spin ice compounds. In addition, we observed the anomaly in specific heat indicating the phase transition to quantum spin ice state.