Science论文导读 | 绝缘体中电阻率的量子振荡

When a metal is cooled to low temperatures and placed in an external magnetic field, its resistivity may oscillate as the magnitude of the field is varied. Seeing these so-called quantum oscillations in an insulating material would be very unusual. Xiang et al. report such findings in the insulator ytterbium dodecaboride (YbB12) (see the Perspective by Ong). In addition to oscillations in resistivity, the authors observed oscillations in the magnetic torque. The results present a challenge to theories that aim to explain the insulating state of YbB12.

当金属冷却至低温并置于外部磁场中时，其电阻率可能会随着磁场的大小变化而振荡。鉴于这些所谓的量子振荡在绝缘材料中是非常罕见的。本文研究人员报道了在绝缘体十二硼化镱(YbB 12)中发现的量子振荡(见Ong的展望)现象。除了电阻振荡外，研究者们还观察到了磁矩振荡。这些结果对于此前解释YbB12绝缘状态的理论提出了挑战。

摘要

In metals, orbital motions of conduction electrons on the Fermi surface are quantized in magnetic fields, which is manifested by quantum oscillations in electrical resistivity. This Landau quantization is generally absent in insulators. Here, we report a notable exception in an insulator—ytterbium dodecaboride (YbB12). The resistivity of YbB12, which is of a much larger magnitude than the resistivity in metals, exhibits distinct quantum oscillations. These unconventional oscillations arise from the insulating bulk, even though the temperature dependence of the oscillation amplitude follows the conventional Fermi liquid theory of metals with a large effective mass. Quantum oscillations in the magnetic torque are also observed, albeit with a lighter effective mass.

在金属中，传导电子在费米表面的轨道运动在磁场中是量子化的，表现为电阻率的量子振荡。兰道通电在绝缘体中通常是不存在的。在本文中，研究者报道了明显的特例，即绝缘体十二硼化镱(YbB12)。YbB12的电阻率比金属的电阻率大得多，且表现出明显的量子振荡。这些非常规振荡产生于绝缘体，尽管振荡振幅随温度的变化依赖于传统费米液体理论，但有效质量很大。在磁矩中也观察到量子振荡，尽管有效质量较轻。