Eur. Phys. J. B (2013) 86: 273
https://doi.org/10.1140/epjb/e2013-40014-7

Regular Article

Vacancy induced magnetism in WO₃

¹ Department of Materials Science and Engineering, KTH Royal Institute of Technology, 100 44 Stockholm, Sweden
² Department of Physics, University of Oslo, P.O. Box 1048 Blindern, 0316 Oslo, Norway

^a e-mail: Gustavo.Baldissera@mse.kth.se

Received: 8 January 2013
Received in final form: 17 April 2013
Published online: 17 June 2013

Abstract

The possibility to obtain ferromagnetic (FM) phase from native defects in WO₃ is investigated by theoretically analyzing six different crystalline structures. The local magnetic moment from vacancies is calculated using the projector augmented wave method in combination with the local spin density approximation including a Coulomb correction (LSDA + U) of the W d-states. We find that tungsten vacancies V_W can induce a magnetic phase of ~3.5μ_B/V_W with a local magnetic moment on the oxygen atoms of at most ~1μ_B/V_W, whereas corresponding oxygen vacancies V_O have no impact on the magnetic coupling. Intriguingly, although the six crystalline structures have very comparable bonds, the magnetic moment generated by the cation vacancies is different, showing higher local magnetic moments for WO₃ structures with low crystalline symmetry. The results indicate that WO₃:V_W cannot induce a hole-mediated FM phase, and instead V_W in WO₃ induces a local magnetic moment on the unpaired states at surrounding O atoms.