Cr3X4 (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 Cr3Te4 nanosheets, herein, to explore their potential application in spintronics, we designed spintronic devices based on Cr3X4 (X = Se, Te) monolayers and investigated their spin transport properties. We found that the Cr3Te4 monolayer based device shows spin filtering and a dual-spin diode effect when applying a bias voltage, while the Cr3Se4 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 Cr3Te4 and Cr3Se4 monolayers, respectively. Interestingly, the current in the Cr3Se4 monolayer based device also displays a negative differential resistance effect (NDRE) and a high magnetoresistance ratio (up to 2 x 10(3)). Moreover, we found a thermally induced spin filtering effect and a NDRE at the Cr3Se4 junction under a temperature gradient instead of a bias voltage. These theoretical findings highlight the potential of Cr3X4 (X = Se, Te) monolayers in spintronic applications and put forward realistic materials to realize nanoscale spintronic devices.