Study of spin liquid states under geometrical frustration

为了探索自旋液体材料自旋激发的本质，我们测量了有机化合物κ-(BEDT-TTf)_2Cu2(CN)_3和EtMe_3Sb[Pd(Dmit)_2]_2的热导率，它们在最低温度下都具有非长程有序状态，即所谓的“自旋液体状态”。我们发现κ-(BEDT-TTf)_2Cu2(CN)_3的激发是有间隙的，因此它是有间隙的自旋液体。另一方面，EtMe_3Sb[Pd(Dmit)_2]_2的热导率表现出与金属非常相似的温度依赖关系，尽管该材料是绝缘体。

To explore the nature of spin excitations of spin liquid material, we have measured thermal conductivity of organic compounds κ-(BEDT-TTF)_2Cu_2(CN)_3 and EtMe_3Sb[Pd(dmit)_2]_2, which are known to possess no-long-range ordered stat-so called "spin liquid state"-down to the lowest temperature. We found the excitation of κ-(BEDT-TTF)_2Cu_2(CN)_3 is gapped, so it is a gapped spin liquid. On the other hand, thermal conductivity of EtMe_3Sb[Pd(dmit)_2]_2 shows a temperature dependence very similar to metal, even though the material is insulator.