Iman S. Roqan, S Venkatesh , Z Zhang , S Hussain , I Bantounas , J , T Flemban , B Zou , J-S Lee , U Schwingenschlogl , P Krastev Petrov , M P Ryan , N M. Alford, Obtaining strong ferromagnetism in diluted Gd-doped ZnO thin films through controlled Gd-defect complexes, Journal of Applied Physics, Volume 117, Issue 7, 2015.
We demonstrate the fabrication of reproducible long-range ferromagnetism FM in highly crystalline GdxZn1_xO thin films by controlling the defects. Films are grown on lattice-matched substrates by pulsed laser deposition at low oxygen pressures 25mTorr and low Gd concentrations x0.009. These films feature strong FM 10lBperGdatom at room temperature. While films deposited at higher oxygen pressure do not exhibit FM, FM is recovered by post-annealing these films under vacuum. These findings reveal the contribution of oxygen deficiency defects to the long-range FM. We demonstrate the possible FM mechanisms, which are confirmed by density functional theory study, and show that Gd dopants are essential for establishing FM that is induced by intrinsic defects in these films.
DOI: 10.1063/1.4908288