First Principles Calculations on Magnetism of CrPt₃(001) Thin Films

Abstract

Recent study shows that ordered alloy of L1 2 XPt 3 (M = V, Cr, Mn, Co, and Fe) exhibits various magnetic phases such as ferromagnetic-to-antiferromagnetic transition at the MnPt 3 surface. Moreover, it has been argued that CrPt 3 , in particular, possess large magnetocrystalline anisotropy and Kerr rotation with possible violation of Hund's rule. As such, we extend our work to thickness dependence of the magnetic structure of CrPt 3 thin film using density functional theory. Magnetic ground state of the bulk CrPt 3 turns out to be ferromagnetic (FM), where other magnetic phases such as A-type (A-AF), C-type (C-AF), and G-type antiferromagnetic (G-AF) state have higher total energies than FM by 0.517, 0.591, and 0.183 eV, respectively, and magnetic moments of Cr in bulk are respectively 2.807 (FM), 2.805 (A-AF), 2.794 (C-AF) and 2.869 µ B (G-AF). We extend our study to CrPt 3 (001) thin films with CrPtand Pt-termination. The thickness and surface-termination dependences of magnetism are investigated for 3-9 monolayers (ML), where different magnetic phases from bulk emerge: C-AF for CrPt-terminated 3 ML and G-AF for Pt-terminated 5 ML have energy difference relative to FM by 8 and 54 meV, respectively. Furthermore, thickness-and surface-termination-dependent magnetocrystalline anisotropies of the CrPt