Two distinct types of magnetism aligned perpendicular in a single crystal have been detailed in new measurements on single-crystal and powered samples composed of barium, potassium, manganese, and arsenic. Antiferromagnetism occurs with a checkerboard-style patterning of the total atomic magnetic moments due to the spins of the localized electrons of the manganese atoms (known as ‘local-moment magnetism’). Aligning perpendicular to the antiferromagnetic order, ferromagnetism (where all electron spins point in the same direction) also occurs, but is assigned specifically to the mobile charges associated with a conduction band formed out of the electrons of the arsenic. XMCD (X-ray Magnetic Circular Dichroism) measurements involve obtaining the difference between two x-ray absorption spectra, one taken with clockwise circularly polarized light and the other with counterclockwise circularly polarized light, in order to observe ferromagnetism associated with specific elements within the material. These measurements were performed at the DOE’s Advanced Photon Source located at Argonne National Laboratory. This material provides a unique opportunity to study two different types of magnetic order coexisting in a single sample.
Itinerant Ferromagnetism in the As 4p Conduction Band of Ba0.6K0.4Mn2As2 Identified by X-Ray Magnetic Circular Dichroism