Itinerant Ferromagnetism in the As $4p$ Conduction Band of ${\mathrm{Ba}}_{0.6}{\mathrm{K}}_{0.4}{\mathrm{Mn}}_{2}{\mathrm{As}}_{2}$ Identified by X-Ray Magnetic Circular Dichroism

Itinerant Ferromagnetism in the As $4 p$ Conduction Band of ${Ba}_{0.6} K_{0.4} {Mn}_{2} {As}_{2}$ Identified by X-Ray Magnetic Circular Dichroism

B. G. Ueland, Abhishek Pandey, Y. Lee, A. Sapkota, Y. Choi, D. Haskel, R. A. Rosenberg, J. C. Lang, B. N. Harmon, D. C. Johnston, A. Kreyssig, and A. I. Goldman

Phys. Rev. Lett. 114, 217001 – Published 27 May 2015

Abstract

X-ray magnetic circular dichroism (XMCD) measurements on single-crystal and powder samples of ${Ba}_{0.6} K_{0.4} {Mn}_{2} {As}_{2}$ show that the ferromagnetism below $T_{C} \approx 100 K$ arises in the As $4 p$ conduction band. No XMCD signal is observed at the Mn x-ray absorption edges. Below $T_{C}$ , however, a clear XMCD signal is found at the As $K$ edge which increases with decreasing temperature. The XMCD signal is absent in data taken with the beam directed parallel to the crystallographic $c$ axis indicating that the orbital magnetic moment lies in the basal plane of the tetragonal lattice. These results show that the previously reported itinerant ferromagnetism is associated with the As $4 p$ conduction band and that distinct local-moment antiferromagnetism and itinerant ferromagnetism with perpendicular easy axes coexist in this compound at low temperature.

Received 30 November 2014

DOI:https://doi.org/10.1103/PhysRevLett.114.217001

Authors & Affiliations

B. G. Ueland^1,2,*, Abhishek Pandey^1,2, Y. Lee^1,2, A. Sapkota^1,2, Y. Choi³, D. Haskel³, R. A. Rosenberg³, J. C. Lang³, B. N. Harmon^1,2, D. C. Johnston^1,2, A. Kreyssig^1,2, and A. I. Goldman^1,2

¹Ames Laboratory, U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, USA
²Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
³Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA