Effect of Biaxial Strain on the Electronic and Magnetic Properties of CuFeS₂

Antiferromagnetic materials are robust in external magnetic fields. This, along with demonstrated high-frequency switching, enables the development of high-speed electronics. Here, magnetic semiconductors present an opportunity, as they enable doping and epitaxial strain to fine-tune their properties. CuFeS₂ is a thermoelectric, low-bandgap semiconductor and collinear antiferromagnet, with a Néel temperature above 800 K, making it a potential candidate for spin-based devices. Here, we investigate strain-engineering as a tool for controlling physical properties of CuFeS₂, and present a density functional theory (DFT) study on the effect of bi-axial strain on CuFeS₂. Neither tensile, nor compressive, bi-axial strain, +/- 5 %, alters the crystal structure or symmetry. However, the calculations show a small change in magnetic moments with strain, increasing under tensile and decreasing under compressive strain for Fe. For Cu atoms the magnetic moment increases for both tensile and compressive strain. The emergence of a small magnetic moment on the Cu atoms has previously been observed experimentally. The magnetic structure will be compared with changes in the band structure, density of state and the nature of the bands near the Fermi level in order to understand the effect of strain on the transport properties.