Hall Anomaly, Quantum Oscillations and Possible Lifshitz Transitions in Kondo Insulator YbB12 : Evidence for Unconventional Charge Transport
Hall Anomaly, Quantum Oscillations and Possible Lifshitz Transitions in Kondo Insulator YbB12 : Evidence for Unconventional Charge Transport
复制标题
DOI：
10.1103/physrevx.12.021050
复制
发表时间：
2021-11
影响因子：
12.5
通讯作者：
Z. Xiang;Kuan-Wen Chen;Lu Chen;T. Asaba;Yuki Sato;Nan Zhang;Dechen Zhang;Y. Kasahara;F. Ig
中科院分区：
文献类型：
--
作者：
Z. Xiang;Kuan-Wen Chen;Lu Chen;T. Asaba;Yuki Sato;Nan Zhang;Dechen Zhang;Y. Kasahara;F. Ig
在相关电子系统中，不同自由度之间的强相互作用和相互作用可能会引起反常的电荷输运性质，这种性质可以通过温度和磁场等外部参数来调节。最近，在近藤绝缘体YBB{12}$中观察到了磁量子振荡和金属低温热导率，其电阻率比常规金属高出几个数量级。到目前为止，这些不同寻常的观察结果还没有完全被理解。在这里，我们用输运测量和扭矩磁测量详细地研究了强磁场下YBB_(12)$的行为。在两个特征磁场($MU_0H_1=19.6$T和$\MU_0H_2\SIM 31$T)下，霍尔系数、磁矩和磁阻出现了特征信号，这使人想起与“奇异金属”物理有关的霍尔响应。我们认为它们很可能是场诱导的Lifshitz相变。此外，在35T以上，本底电阻率表现出不同寻常的非金属α行为，它与场有关，在-1.5和-2之间变化。通过将Shubnikov-de Haas振荡幅度归一化为这种依赖关系，计算得到的回旋质量与由de Haas-van Alphen振荡得到的结果更加一致。我们的结果支持YBB中一种新的双流体情景：由电荷中性准粒子组成的类费米液体流体与保持非金属状态的电荷载流子共存。前者经历了连续的Lifshitz相变，并在外加磁场中发展了朗道量子化，而两种流体之间的散射允许在电子输运中观察到Shubnikov-de Haas效应。
In correlated electronic systems, strong interactions and the interplay between different degrees of freedom may give rise to anomalous charge transport properties, which can be tuned by external parameters like temperature and magnetic field. Recently, magnetic quantum oscillations and metallic low-temperature thermal conductivity have been observed in the Kondo insulator YbB$_{12}$, whose resistivity is a few orders of magnitude higher than those of conventional metals. As yet, these unusual observations are not fully understood. Here we present a detailed investigation of the behavior of YbB$_{12}$ under intense magnetic fields using both transport and torque magnetometry measurements. A low-field Hall anomaly, reminiscent of the Hall response associated with"strange-metal"physics, develops at $T<1.5$ K. At two characteristic magnetic fields ($\mu_0H_1= 19.6$ T and $\mu_0H_2 \sim 31$ T), signatures appear in the Hall coefficient, magnetic torque, and magnetoresistance. We suggest that they are likely to be field-induced Lifshitz transitions. Moreover, above 35 T, the background resistivity displays an unusual, nonmetallic $T^{\alpha}$-behavior, with $\alpha$ being field-dependent and varying between -1.5 and -2. By normalizing the Shubnikov-de Haas oscillation amplitude to this $T^{\alpha}$-dependence, the calculated cyclotron mass becomes more consistent with that deduced from de Haas-van Alphen oscillations. Our results support a novel two-fluid scenario in YbB$_{12}$: a Fermi-liquid-like fluid of charge-neutral quasiparticles coexists with charge carriers that remain in a nonmetallic state. The former experience successive Lifshitz transitions and develop Landau quantization in applied magnetic fields, whilst scattering between both fluids allows the Shubnikov-de Haas effect to be observed in the electrical transport.