XMCD and PES study of a compensated-ferrimagnetic half-metal Mn3Ga

By employing soft X-ray magnetic circular dichroism (XMCD), soft X-ray absorption spectroscopy (XAS), and photoemission spectroscopy (PES), we have investigated the electronic structure of the candidate zero-moment half-metallic Mn3Ga. We have studied the ball-milled and annealed Mn3Ga powder samples that exhibit nearly zero magnetization. Mn 2p XAS revealed that Mn ions in Mn3Ga are nearly divalent for both of the Mn ions having the locally octahedral symmetry and those having the locally tetrahedral symmetry. The measured Mn 2p XMCD spectrum of Mn3Ga is very similar to that of ferrimagnetic MnFe2O4 having divalent Mn ions. The sum-rule analysis of the Mn 2p XMCD spectrum shows that both the spin and orbital magnetic moments of Mn ions in Mn3Ga are negligibly small, in agreement with the nearly compensated-ferrimagnetic ground state of Mn3Ga. The valence-band PES spectrum of Mn3Ga agrees well with the calculated density of states, supporting the half-metallic electronic structure of Mn3Ga.