First-Principles Study on the Tunable Electronic and Magnetic Properties of a Janus GaInSeTe Nanosheet via Strain and Defect Engineering

Recently, Janus two-dimensional (2D) materials have gained much attention due to their intrinsic vertical dipole. Here, we extensively investigate the electronic and magnetic properties of a new type of two-dimensional graphene-like Janus GaInSeTe monolayer by adopting the first- principles methods based on the density functional theory. It is found that 2D Janus GaInSeTe exhibits high dynamical stability and acts as a direct band gap semiconductor. The novel electronic and magnetic properties of the GaInSeTe nanosheet can be modulated via biaxial strain and atomic-sized structural defects. Specifically, the significant changes of semiconductor-to-metal and direct-to-indirect semiconductor transitions are driven by the biaxial strain. Our results also confirm that different types of single vacancy and multiple vacancy can effectively alter the electronic and magnetic properties of the GaInSeTe monolayer. Depending on the different vacancies, they induce metallic (V-Ga and V-In), direct band-gap semiconductive (V-Se, V-GaIn and V-GaInTeSe) and indirect band-gap semiconductor (V-Te, V-TeSe), respectively. It was also found that the inclusion of an In vacancy induces magnetism in the Janus GaInSeTe monolayer. Moreover, results show that the electronic and magnetic properties of Janus GaInSeTe monolayer are significantly modulated by vacancies and the external strains, and it displays varied band gaps of magnetic or nonmagnetic, multiple magnetic moments in semiconducting or metallic structures. These tunable electronic structure and magnetic properties of the Janus GaInSeTe monolayer can be utilized for the development of low-dimensional spintronics devices. Graphical Abstract The electronic and magnetic properties of a Janus GaInSeTe monolayer are significantly modulated by vacancies and the external strain, and it displays varied magnetic or nonmagnetic band gaps and multiple magnetic moments in semiconducting or metallic structures. [GRAPHICS]