Electronic, magnetic and optical properties of various surfaces of TiHfIrZ (Z = Al and Ga) quaternary Heusler alloy

The electronic, magnetic and optical properties of (001), (110) and (111) surfaces of TiHfIrZ (Z = Al and Ga) quaternary Heusler alloy are studied by the first-principles method. All the seven surfaces investigated lose the bulk half-metallicity, and the TiHfIrZ-terminated (110) and Ti-terminated (111) surfaces of TiHfIrZ (Z = Al and Ga) with the high spin polarization are more suitable for the spintronics application using generalized gradient approximation (GGA) method. While the TiHfIrZ-terminated (110) surfaces of TiHfIrZ (Z = Al and Ga) present half-metallicity using the GGA + U method. The change of the bond lengths affects the d-d and p-d hybridization, and the atomic restrictions of the atoms, thus the electronic, magnetic and optical properties of the surfaces are different from those in the bulk alloy. The Ti-terminated (111) and TiHfIrZ(Z = Al and Ga)-terminated (110) surfaces are suitable for using in the infrared light transmission. The TiHfIrZ (Z = Al and Ga)-terminated (110) surface is suitable for using in both the infrared light transmission and the visual light absorption.