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 × 10³). 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.