Anisotropic Spin Distribution and Perpendicular Magnetic Anisotropy in a Layered Ferromagnetic Semiconductor (Ba,K)(Zn,Mn)2As2

The perpendicular magnetic anisotropy of a layered ferromagnetic semiconductor (Ba,K)(Zn,Mn)(2)As-2 is studied using angle-dependent X-ray magnetic circular dichroism (XMCD) measurements. The large magnetic anisotropy with an anisotropy field of 0.85 T is deduced by fitting the Stoner-Wohlfarth model to the magnetic-field angle dependence of the projected magnetic moment. Transverse XMCD spectra highlight the anisotropic distribution of Mn 3d electrons, where the d(xz), and d(yz), orbitals are less populated than the d(xy) state because of the D-2d splitting that arises from the elongated MnAs4 tetrahedra. The magnetic anisotropy originates from the degeneracy lifting of p-d(xz), d(yz) hybridized states at the Fermi level. Namely, spin-orbit coupling lifts their degeneracy and induces energy gain when spins align along the z direction. The present system offers another tuning knob to control magnetic anisotropy through atomic orbital engineering.