Cr 3 X 4 (X = Se, Te) monolayers as a new platform to realize robust spin filters, spin diodes and spin valves.

Two-dimensional ferromagnetic (FM) half-metals are promising candidates for advanced spintronic devices with small size and high capacity. Motivated by a recent report on controlling the synthesis of FM Cr 3 Te 4 nanosheets, herein, to explore their potential application in spintronics, we designed spintronic devices based on Cr 3 X 4 (X = Se, Te) monolayers and investigated their spin transport properties. We found that the Cr 3 Te 4 monolayer based device shows spin filtering and a dual-spin diode effect when applying a bias voltage, while the Cr 3 Se 4 monolayer is an excellent platform to realize a spin valve. These different transport properties are primarily ascribed to the semiconducting spin channel, which is close to and away from the Fermi level in Cr 3 Te 4 and Cr 3 Se 4 monolayers, respectively. Interestingly, the current in the Cr 3 Se 4 monolayer based device also displays a negative differential resistance effect (NDRE) and a high magnetoresistance ratio (up to 2 × 10 3 ). Moreover, we found a thermally induced spin filtering effect and a NDRE at the Cr 3 Se 4 junction under a temperature gradient instead of a bias voltage. These theoretical findings highlight the potential of Cr 3 X 4 (X = Se, Te) monolayers in spintronic applications and put forward realistic materials to realize nanoscale spintronic devices.