arXiv subjects

Francois Baudelet

Publications and source records attributed to Francois Baudelet.

2 recordsLinked to original sources

arXiv2020

Room-temperature ferrimagnetism of anti-site-disordered Ca2MnOsO6

Room-temperature ferrimagnetism was discovered for the anti-site-disordered perovskite Ca2MnOsO6 with Tc = 305 K. Ca2MnOsO6 crystallizes into an orthorhombic structure with a space group of Pnma, in which Mn and Os share the oxygen-coordinated-octahedral site at an equal ratio without a noticeable ordered arrangement. The material is electrically semiconducting with variable-range-hopping behavior. X-ray absorption spectroscopy confirmed the trivalent state of the Mn and the pentavalent state of the Os. X-ray magnetic circular dichroism spectroscopy reveals that the Mn and Os magnetic moments are aligned antiferromagnetically, thereby classifying the material as a ferrimagnet which is in accordance with band structure calculations. It is intriguing that the magnetic signal of the Os is very weak, and that the observed total magnetic moment is primarily due to the Mn. The Tc = 305 K is the second highest in the material category of so-called disordered ferromagnets such as CaRu1-xMnxO3, SrRu1-xCrxO3, and CaIr1-xMnxO3, and hence, may support the development of spintronic oxides with relaxed requirements concerning the anti-site disorder of the magnetic ions.

cond-mat.str-el↗

arXiv2004

XMCD under pressure at the Fe K edge on the energy dispersive beamline of the ESRF

The present paper demonstrates the feasibility of X-ray Absorption Spectroscopy (XAS) and X-ray Magnetic Circular Dichroism (XMCD) at high pressure at the Fe-K edge on the ID24 energy dispersive beamline of the ESRF. In 3d transition metals, performing experiments at the hard X-ray K-edge rather than at the magnetically interesting soft X-ray L-edges represents, the only way to access the high pressure regime obtainable with Diamond Anvil Cells. The simultaneous availability of a local structure (XAS) and of a magnetic (XMCD) probe on the sample in identical thermodynamical conditions is essential to study correlations between local structural and magnetic properties. We briefly summarize the state of the art theoretical understanding of K-edge XMCD data, then illustrate the setup of beamline ID24 for high pressure XMCD experiments and underline the conditions required to perform measurements at the K-edges of 3d transition metals. Finally, we present two examples of recent high pressure results at the Fe-K edge in pure Fe and Fe3O4 powder.

physics.ins-det↗