Enhanced perpendicular magnetic anisotropy energy and Curie temperature in the CrOCl monolayer: strain effects

Abstract Magnetic monolayers offer a wide variety of applications in enhancing the functionalities of storage devices including higher thermal stability, lower power consumption, and higher operation speed, owing to their intrinsic long-range spin ordering. Herein, we study the biaxial ([110]) strain range of ± 5% influence on the formation energetics, electronic structure, and magnetic behaviour of the CrOCl monolayer (ML) based on the ab -initio calculations including spin–orbit coupling (SOC) effects. It is predicted that the system displays an insulating character having an energy band gap ( E g ) of 2.05 eV with a ferromagnetic (FM) ground state in its unstrained state. The estimated partial spin magnetic moment on the Cr ion is +2.7 μ B /f.u. (per formula unit) with S = 1.5 and lies in a + 3 oxidation state with an electronic distribution of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>t</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> <mml:mi>g</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>↑</mml:mo> <mml:msubsup> <mml:mrow> <mml:mi>t</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> <mml:mi>g</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>↓</mml:mo> <mml:msubsup> <mml:mrow> <mml:mi>e</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>g</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>↑</mml:mo> <mml:msubsup> <mml:mrow> <mml:mi>e</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>g</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>↓</mml:mo> </mml:math> . Along with this, [001] ( c -axis) is found to be the easy magnetic axis, which results in a magnetic anisotropy energy (MAE) of 0.2 meV having an MAE constant of 0.25 mJ m −2 and the computed Curie temperature ( T c ) using Ising model is 157 K. Furthermore, the system shows the robustness of the FM insulating behavior against considered strains. However, a significant shift in the conduction band edge (CBE) position to lower energies is evident for tensile strains, which substantially reduces the E g up to 13%. The decrease in E g value is evidence of higher absorption in the visible range which makes it the best option for optoelectronics and photocatalysis. Simultaneously, our results revealed that strain enhances the MAE and T c up to 190% and 43%, respectively. Hence, optimized E g , MAE, and T c within a considerable strain range, make the CrOCl ML a potential candidate for its utilization in magnetic memory devices.