Metal-insulator transition (MIT) is one of the most conspicuous phenomena in correlated electron systems. However such transition has rarely been induced by an external magnetic field as the field scale is normally too small compared with the charge gap. In this paper we present the observation of a magnetic-field-driven MIT in a magnetic semiconductor $\beta $-EuP$_3$. Concomitantly, we found a colossal magnetoresistance (CMR) in an extreme way: the resistance drops billionfold at 2 kelvins in a magnetic field less than 3 teslas. We ascribe this striking MIT as a field-driven transition from an antiferromagnetic and paramagnetic insulator to a spin-polarized topological semimetal, in which the spin configuration of $\mathrm{Eu^{2+}}$ cations and spin-orbital coupling (SOC) play a crucial role. As a phosphorene-bearing compound whose electrical properties can be controlled by the application of field, $\beta $-EuP$_3$ may serve as a tantalizing material in the basic research and even future electronics.

中文翻译：

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β-EuP3 中的场致金属-绝缘体转变

金属绝缘体跃迁 (MIT) 是相关电子系统中最显着的现象之一。然而，这种转变很少由外部磁场引起，因为与电荷间隙相比，场尺度通常太小。在本文中，我们展示了对磁性半导体 $\beta $-EuP$_3$ 中磁场驱动的 MIT 的观察。同时，我们以一种极端的方式发现了巨大的磁阻 (CMR)：在小于 3 特斯拉的磁场中，电阻在 2 开尔文时下降了十亿倍。我们将这种惊人的 MIT 归因于从反铁磁和顺磁绝缘体到自旋极化拓扑半金属的场驱动转变，其中 $\mathrm{Eu^{2+}}$ 阳离子的自旋配置和自旋轨道耦合（ SOC）起着至关重要的作用。