Correlation between Mn and Ru valence states and magnetic phases in SrMn1-xRuxO3

Abstract

The electronic structures of SrMn1-xRuxO3 (0 <= x <= 1) have been investigated by employing soft x-ray absorption spectroscopy (XAS) and soft x-ray magnetic circular dichroism (XMCD). Both Mn and Ru ions are nearly tetravalent (Mn4+, Ru4+) for the end members of x = 0 (SrMnO3) and x = 1 (SrRuO3). In the Ru-dilute concentration (x <= similar to 0.2), Ru ions are pentavalent (Ru5+), which transform neighboring Mn ions into the trivalent Mn3+ states via electron charge transfer. In the intermediate substitution regime, Mn and Ru ions are in the inhomogeneously mixed-valent states (Mn-3 - Mn4+ and Ru-4 - Ru5+). Finite Mn 2p XMCD signals are observed for x > 0, in agreement with the ferromagnetic, spin-glass, cluster-glass ground states depending on x. The unoccupied Mn 3d and Ru 4d states, determined from the measured O 1s XAS spectra and the calculated density of states, support these findings.