Eur. Phys. J. B (2017) 90: 118
https://doi.org/10.1140/epjb/e2017-70495-y

Regular Article

Ab initio exploration of d⁰ digital magnetic heterostructures: the case of MgO and CaO δ-doped with potassium ^*

¹ Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Faculty of Science, Tianjin University, Tianjin 300072, P.R. China
² Department of Physics, Tianjin Normal University, Tianjin 300387, P.R. China

^a e-mail: fengliefeng@tju.edu.cn

Received: 24 August 2016
Received in final form: 10 January 2017
Published online: 21 June 2017

Abstract

Previous studies of digital magnetic heterostructures have mainly focused on 3d transition metal δ-doped semiconductors. In this work, sp-electron digital magnetic heterostructures without magnetic ions are proposed. Based on a theoretical density functional investigation, electronic structures and magnetic properties of MgO and CaO δ-doped with K were reported. The results show that these heterostructures are half-metallic ferromagnetic materials having semiconducting up spins and metallic down spins, with an exchange interaction much stronger than that of a random alloy with similar K concentration. Our first-principles calculations show that the carriers at the Fermi level are strongly confined within a few monolayers around the KO plane. This strong confinement is responsible for the large exchange coupling and the two-dimensional half-metallic behavior. The thickness of the host semiconducting spacer does not significantly change the global electric and magnetic features.