Predicted intrinsic piezoelectric ferromagnetism in Janus monolayer MnSbBiTe4: a first principles study

Two-dimensional (2D) piezoelectric ferromagnetism (PFM) is essential for the development of the next-generation multifunctional spintronic technologies. Recently, the layered van der Waals (vdW) compound MnBi2Te4 as a platform to realize the quantum anomalous Hall effect (QAHE) has attracted great interest. In this work, the Janus monolayer MnSbBiTe4 with dynamic, mechanical and thermal stabilities is constructed from a synthesized non-piezoelectric MnBi2Te4 monolayer by replacing the top Bi atomic layer with Sb atoms. The calculated results show that monolayer MnSbBiTe4 is an intrinsic ferromagnetic (FM) semiconductor with a gap value of 0.25 eV, whose easy magnetization axis is out-of-plane direction with magnetic anisotropy energy (MAE) of 158 mu eV per Mn. The predicted Curie temperature T-C is about 20.3 K, which is close to that of monolayer MnBi2Te4. The calculated results show that the in-plane d(11) is about 5.56 pm V-1, which is higher than or comparable to those of other 2D known materials. Moreover, it is found that strain engineering can effectively tune the piezoelectric properties of Janus monolayer MnSbBiTe4. The calculated results show that tensile strain can improve the d(11), which is improved to be 21.16 pm V-1 at only 1.04 strain. It is proved that the ferromagnetic order, semiconducting properties, out-of-plane easy axis and a large d(11) are robust against electronic correlations. Our work provides a possible way to achieve PFM with a large d(11) in well-explored vdW compound MnBi2Te4, which makes it possible to use the piezoelectric effect to tune the quantum transport process.

Automated summary

This study constructs a Janus monolayer MnSbBiTe4 with dynamic, mechanical, and thermal stabilities by replacing the top Bi atomic layer of a synthesized non-piezoelectric MnBi2Te4 monolayer with Sb atoms. The monolayer exhibits intrinsic ferromagnetic semiconductor properties, with an out-of-plane easy magnetization axis and a large d(11) value that can be effectively tuned through strain engineering. The robustness of its ferromagnetic order, semiconducting properties, and large d(11) value against electronic correlations is demonstrated, providing a potential pathway to achieve piezoelectric ferromagnetism with a large d(11) in well-known vdW compound MnBi2Te4.