Obtaining strong ferromagnetism in diluted Gd-doped ZnO thin films through controlled Gd-defect complexes

作者：Iman S. Roqan, S. Venkatesh, Z. Zhang, Shahid Hussain, Ioannis Bantounas, Joseph B. Franklin, Tahani H. Flemban, Bin Zou, J.-S. Lee, Udo Schwingenschlögl, Peter K. Petrov, Mary P. Ryan, Neil McN. Alford · 发表于：Journal of Applied Physics · 年份：2015 · DOI：10.1063/1.4908288 · 被引用次数：61 · 研究领域：ZnO doping and properties、Advanced Condensed Matter Physics、Magnetic and transport properties of perovskites and related materials

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 (≤25 mTorr) and low Gd concentrations (x ≤ 0.009). These films feature strong FM (10 μB per Gd atom) 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.