Strain controlled antiferromagnetic insulating state along with ferroelectricity and magnetic anisotropy in Pb2CoTeO6

Abstract

Controlling electronic and magnetic properties of materials by strain engineering is essential and extremely sought for high-performance spintronic devices as strain can be easily achieved experimentally. In this respect, antiferromagnetic (AFM) double perovskite oxides (DPO) have attracted a lot of attention due to ultrafast spin moments and small stray field, which is potentially desired for high-frequency and high-data storage devices. Herein, the electronic, magnetic, and ferroelectric properties of Pb 2 CoTeO 6 DPO under uniaxial ([100], [010], and [001]), biaxial ([110]), and hydrostatic ([111]) strains are investigated in the framework of first-principles calculations including Hubbard parameter U . Pristine motif emerges as AFM insulator having an indirect energy band gap of 1.88 eV due to anti-alignment of Co ions at the diagonal. The most striking feature of the present study is that system exhibits a substantial magnitude of spontaneous polarization of 32 μ C/cm 2 and magnetocrystalline anisotropy constant of 5.4 × 10 7 erg/cm 3 with an easy axis of [011]. Moreover, it is found that Co lies in a ＋ 2 state having an electronic configuration of t 2 g 3 ↑ e g 2 ↑ t 2 g 2 ↓ e g 0 ↓ with S= 1.5 and displays a spin moment of 2.71 μ B . The solidity of AFM state and robustness of the insulating nature is confirmed under the influence of strains. An indirect to direct band gap transition is established for compressively strained motifs, which is useful for optics as well as the solar cell industry. Finally, it is revealed that overall compressive and tensile strains show a negative and positive impact on the spontaneous polarization amplitude, respectively. • Anti-ferromagnetic (AFM) super-exchange coupling leads the system to AFM ground state. • System exhibits a reasonable magnitude of magnetic anisotropy energy constant. • The solidity of AFM state and robustness of the insulating nature is confirmed under the influence of strains. • A substantial amplitude of spontaneous polarization of 32 μ C/cm 2 .