Awaking of ferromagnetism in GaMnN through control of Mn valence

Abstract

Room temperature ferromagnetism of GaMnN thin films is awaked by a mild hydrogenation treatment of samples synthesized by molecular beam epitaxy. Local environment of Mn atoms is monitored by Mn-L2,3 near edge x-ray absorption fine structure (NEXAFS) technique. Doped Mn ions are present at substitutional sites of Ga both before and after the hydrogenation. No secondary phase can be detected. Major valency of Mn changes from +3 to +2 by the hydrogenation. The present result supports the model that the ferromagnetism occurs when Mn2+ and Mn3+ are coexistent and holes in the mid- gap Mn band mediate the magnetic coupling.Comment: 12 pages, 5 figure

Effects of growth temperature on the valence, optical and magnetic properties of Mn-doped GaN films grown by metal organic chemical vapor deposition

“…5 indicate the paramagnetic behavior of films A, B, and C. Therefore, the magnetic properties of the Mn-doped GaN films are not dependent on the valence of Mn ions. This finding is different from previous theoretical prediction [36] and experimental reports [3,6], where ferromagnetism is scaled with the Mn 3+ . However, the paramagnetism of the films in the present study is 3+ .…”

“…For instance, ferromagnetism occurs in GaN:Mn with Mn 3+ but disappears when Mn 3+ changes to Mn 2+ [2][3][4][5]. Nevertheless, Sonoda et al [6] reported that the coexistence of Mn 2+ and Mn 3+ is a basis of ferromagnetism. In addition, the valence of Mn ions exerts much influence on the optical properties of GaN:Mn.…”

“…However, previous methods to control Mn valence are complicated. These methods include thermal annealing [3], Si codoping [4], Mg codoping [5,12], and hydrogenation [6]. In fact, nitrogen vacancy (V N ) or excess Ga is a kind of donor in GaN.…”

First‐principles study of electronic properties of GaN nanowires: Effect of surface orientation, passivation, and Mn doping

“…It is known that doping with transition metals influences the electronic and magnetic properties of NWs. Experimental work reported on the synthesis of GaMnN material exhibits ferromagnetism at room temperature and depended on the concentration of impurities . Mn ions were present in substitutional sites of Ga ion for both before and after hydrogenation .…”

“…Experimental work reported on the synthesis of GaMnN material exhibits ferromagnetism at room temperature and depended on the concentration of impurities . Mn ions were present in substitutional sites of Ga ion for both before and after hydrogenation . Gao et al successfully synthesized room‐temperature GaMnN film using a laser molecular beam epitaxial method, whose structural and magnetic properties are strongly dependent on the substrate temperature.…”