Magnetic-Field Response and Giant Electric-Field Modulation of Cu<sub>2</sub>S.

Chen, Hongyu; Zhou, Xiaorong; Meng, Ziang; Wang, Xiaoning; Duan, Zhiyuan; Liu, Li; Zhao, Guojian; Yan, Han et al. · Nano Lett · 2024

basic_science · Level V

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Abstract

Cu<sub>2</sub>S likely plays an important role in the sharp resistivity transition of LK-99. Nevertheless, this immediately arouses an intriguing question of whether the extraordinary room-temperature colossal magnetoresistance in the initial reports, which has been less focused, originates from Cu<sub>2</sub>S as well. To resolve this issue, we have systematically investigated the electrical transport and magnetotransport properties of near-stoichiometric Cu<sub>2</sub>S pellets and thin films. Neither Cu<sub>2</sub>S nor LK-99 containing Cu<sub>2</sub>S in this study was found to exhibit the remarkable magnetoresistance effect implied by Lee et al. This implies that Cu<sub>2</sub>S could not account for all of the intriguing transport properties of the initially reported LK-99, and the initially reported LK-99 samples might contain magnetic impurities. Moreover, based on the crystal-structure-sensitive electrical properties of Cu<sub>2</sub>S, we have constructed a piezoelectric-strain-controlled device and obtained a giant and reversible resistance modulation of 2 orders of magnitude at room temperature, yielding a huge gauge factor of 160,000.