Gate-Controlled Magnetotransport and Electrostatic Modulation of Magnetism in 2D Magnetic Semiconductor CrPS₄

By Fan Wu, Nicolas Ubrig and Alberto Morpurgo, UNIGE

The discovery of 2D magnets discloses the possibility to combine semiconducting and magnetic functionalities in a broad platform of atomically thin crystals. Most 2D magnets investigated so far, however, exhibit poor –or very anomalous– semiconducting properties, because the width of their electronic bands is extremely narrow (~100 meV). Narrow bandwidths are detrimental for the electrical conduction in semiconductors as they easily result in electron localization, precluding the realization of field-effect transistors. Indeed, in the 2D magnetic semiconductors investigated so far, transistor action was either entirely absent, or extremely poor.

Our work identifies CrPS₄ as a 2D magnetic semiconductor with an electronic bandwidth much larger than that of other similar materials [1]. The conduction bandwidth approaches 1 eV and we demonstrate that field-effect transistors based on this material allow gate-tunable transport to be measured down to cryogenic temperature (T = 2 K), well below the magnetic transition temperature T_N = 36 K. The devices exhibit a very large, gate-tunable magnetoconductance (reaching 5000%) and allow to map experimentally the magnetic phase diagram of CrPS₄ which hosts multiple phase transitions. The most important result of our work is the ability to control the magnetic state electrostatically in few nanometer thick crystals.

Our results identify CrPS₄ as an extremely interesting 2D magnet for future investigations. For instance, a single atomic layer of CrPS₄ should allow the realization of gate-tunable half-metals, which have been predicted theoretically but not been observed so far. Our work demonstrates that finding 2D magnetic semiconductors with a large electronic bandwidth is a key goal to fully exploit the interplay between magnetic and semiconducting functionality.