Spin transport properties in Dirac spin gapless semiconductors Cr2X3 with high Curie temperature and large magnetic anisotropic energy

Abstract

2D honeycomb-Kagome (HK) lattices have attracted extensive attention in recent years due to the peculiar electronic and magnetic properties such as the Dirac band, the half-metallicity, and the high Curie temperature. In this Letter, we theoretically investigate the spin transport properties of a recently proposed 2D Dirac spin gapless semiconductor (also known as a Dirac half-metal with zero energy gap in one spin channel) of the Cr2S3 monolayer with the HK lattice. The excellent spin filtering effect and negative differential resistance effect are found at a bias voltage, and interestingly, a temperature difference can also drive the spin filtering effect. These peculiar transport properties can be understood from the Dirac spin gapless semiconductivity and the spin-dependent transmission spectrum. In addition, we predict that, similar to Cr2S3 and Cr2Se3, 2D Cr2Te3 is also a Dirac spin gapless semiconductor with the above room-temperature Curie temperature and a large magneto-crystalline anisotropic energy (MAE). Under a tensile biaxial strain, the MAE can be greatly increased, and the easy magnetization axis is still along the in-plane. All these results are achieved by the first-principles combined with nonequilibrium Green's function method. The present work will stimulate theoretical and experimental studies on spintronic devices and spin caloritronic devices based on more 2D Dirac HK lattices.

Two-dimensional spin-gapless semiconductors: A mini-review

“…For the Cr 2 S 3 and Cr 2 Se 3 , the Dirac points along the K-Γ-M paths are still maintained within PBE and HSE06. The effect of SOC to the Dirac points is also examined by Feng, Liu, and Gao ( Feng et al, 2021 ); they stated that the SOC effect is weak for the proposed monolayers.…”

“…Among different types of 2D ferromagnetic materials, 2D spin-gapless semiconductors (SGSs) ( Li et al, 2009 ; Zhang et al, 2015 ; Gao et al, 2016 ; Zhu and Li, 2016 ; Wang et al, 2017a ; He et al, 2017 ; Lei et al, 2017 ; Wang, 2017 ; Deng et al, 2018b ; Wang et al, 2018b ; Wu et al, 2020a ; Yang et al, 2020a ; Wu et al, 2020b ; Deng et al, 2020 ; Feng et al, 2020 ; Li et al, 2020 ; Nadeem et al, 2020 ; Rani et al, 2020 ; Wang et al, 2020 ; Yue et al, 2020 ; Şaşıoğlu et al, 2020 ; Feng et al, 2021 ; Phong and Nguyen, 2022 ) are ideal candidates for high-efficient spintronic devices. Wang ( Wang, 2008 ) first proposed the concept of SGSs in 2008, and the SGSs can be viewed as a bridge to connect the magnetic semiconductors ( Haas, 1970 ; Dietl, 2010 ; Sato et al, 2010 ) and half-metals ( Wang et al, 2016b ; Wang et al, 2017b ; Wang et al, 2017c ; Liu et al, 2017 ; Wang et al, 2018c ; Han et al, 2019 ; Wang et al, 2019 ; Yang et al, 2020b ; Tang et al, 2021 ; Yang et al, 2021 ).…”

“…In 2021, Feng, Liu, and Gao ( Feng et al, 2021 ) proposed the spin-gapless semiconducting states in 2D Cr 2 X 3 monolayers (X = S, Se, and Te) via first-principle calculations. The estimated Curie temperatures for these three monolayers are about 420, 480, and 510 K, respectively.…”

“…(F) The spin-resolved current-voltage curves for the PC and the APC of the device. (A–F) Reproduced from ( Feng et al, 2021 ) with permission from AIP publishing. (G) Schematics for the FM and AFM states of the CrGa 2 Se 4 monolayer.…”

“…Feng, Liu, and Gao ( Feng et al, 2021 ) also studied the nonequilibrium spin transport properties of monolayer Cr 2 S 3 , and the device model is shown in Figure 2E . From Figure 2F , for the APC in both spin directions, one finds the values of spin-currents are extremely small.…”