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arXiv · 1502.02324

Ultraquantum magnetoresistance in single-crystalline $β$-Ag$_2$Se

Chenglong Zhang·Haiwen Li·Tay-Rong Chang·Su-Yang Xu·Wei Hua·Hua Jiang·Zhujun Yuan·Junliang Sun·Horng-Tay Jeng·M. Zahid Hasan·X. C. Xie·Shuang Jia
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Abstract

In the history of condensed matter physics, reinvestigation of a well-studied material with enhanced quality sometimes led to important scientific discoveries. A well-known example is the discovery of fractional quantum Hall effect in high quality GaAs/AlGaAs heterojunctions. Here we report the first single crystal growth and magnetoresistance (MR) measurements of the silver chalcogenide $β$-Ag$_2$Se (Naumannite), a compound has been known for the unusual, linear-field-dependent MR in its polycrystalline form for over a decade. With the quantum limit (QL) as low as 3 Tesla, a moderate field produced by a superconductor magnet available in many laboratories can easily drive the electrons in Ag$_2$Se to an unprecedented state. We observed significant negative longitudinal MR beyond the QL, which was understood as a `charge-pumping' effect between the novel fermions with opposite chiralities. Characterization of the single-crystalline Ag$_2$Se and the fabrication of electric devices working above the QL, will represent a new direction for the study of these exotic electrons.

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Chenglong Zhang, Haiwen Li, Tay-Rong Chang, Su-Yang Xu, Wei Hua, Hua Jiang, Zhujun Yuan, Junliang Sun, Horng-Tay Jeng, M. Zahid Hasan, X. C. Xie, Shuang Jia. 2015-02-09. Ultraquantum magnetoresistance in single-crystalline $β$-Ag$_2$Se. https://doi.org/10.1103/physrevb.96.165148

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