First-Principles Study of Electric Field Effects on Magnetic Anisotropy in Ultrathin Ferromagnetic TM (TM = Fe, Co) Films on Pt(111) Underlayer

We study the electric field (EF) effects on the magnetic anisotropy in the ultrathin ferromagnetic TM (TM = Fe, Co) films on the Pt(111) underlayer using relativistic first-principles calculations based on the density functional theory with a special attention on the effects of Pt segregation. The magnetic anisotropy energy, MAE, and the spin magnetic moment, Mspin, of the Pt/TM/Pt(111) and BeO/Pt/TM/Pt(111) systems as well as those of the TM/Pt(111) and BeO/TM/Pt(111) systems are calculated in the absence of or under the EF. It is found that the MAE and its EF dependence of the BeO/Pt/TM/Pt(111) systems, especially those of the BeO/Pt/Co/Pt(111) system, are considerably large. The sign of the EF dependence is such that the MAE and Mspin are increased (decreased) when the EF increases (decreases) the number of electrons in the system. We attribute this unique behavior to the formation of the hybridized majority-spin states originated in the O 2pz, Pt 5d3z2−r2, and TM 3d orbitals of the interfacial atoms