Solid State Communications 151 (2011) 1794–1797 Contents lists available at SciVerse ScienceDirect Solid State Communications journal homepage: www.elsevier.com/locate/ssc Theoretical study of magnetic ordering and electronic properties of Ag x Al 1-x N compounds Alvaro González-García * , William López-Pérez 1 , Rafael González-Hernández 1 Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Barranquilla, Colombia article info Article history: Received 6 April 2011 Accepted 18 August 2011 by T.T.M. Palstra Available online 25 August 2011 Keywords: A. Aluminum nitride A. Silver C. Diluted magnetic semiconductors E. Density functional calculations abstract Ferromagnetic ordering of silver impurities in the AlN semiconductor is predicted by plane-wave ultrasoft pseudopotential and spin-polarized calculations based on density functional theory (DFT). It was found that an Ag impurity atom led to a ferromagnetic ground state in Ag 0.0625 Al 0.9375 N, with a net magnetic moment of 1.95 μ B per supercell. The nitrogen neighbors at the basal plane in the AgN 4 tetrahedron are found to be the main contributors to the magnetization. This magnetic behavior is different from the ones previously reported on transition metal (TM) based dilute magnetic semiconductor (DMS), where the magnetic moment of the TM atom impurity is higher than those of the anions bonded to it. The calculated electronic structure band reveals that the Ag-doped AlN is p-type ferromagnetic semiconductor with a spin-polarized impurity band in the AlN band gap. In addition, the calculated density of states reveals that the ferromagnetic ground state originates from the strong hybridization between 4d-Ag and 2p-N states. This study shows that 4d transition metals such as silver may also be considered as candidates for ferromagnetic dopants in semiconductors. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction Since 1988 when Giant Magnetoresistive Effect (GME) was discovered by Albert Fert in France and Peter Gruenberg in Germany [1,2], Scientists have been focused on developing new semiconductor spintronic devices. Spintronic applications use both the electrical charge and the spin of electrons to increase considerably the functionality of devices designed with conventional semiconductors [3–5]. In this sense, the interest in the ferromagnetic ordering of dopants in semiconductors has been increased. The interest in spintronics not only motivated the investigation of new magnetic semiconductors but has also recovered the interest in new magnetic metallic materials. The possibility of high-temperature ferromagnetism in dilute magnetic semiconductors (DMSs) has been verified [6], allowing to find materials which reveal room-temperature ferromagnetism [7,8]. Among them, AlN-based DMSs have attracted a significant interest since they become ferromagnetic when doped not only with * Correspondence to: Cra. 43b No 82-146. Apto 2. Barranquilla, Colombia. Tel.: +57 5 3571792; fax: +57 5 3598852. E-mail addresses: alvarogonzalez@uninorte.edu.co, algoga828@hotmail.com (A. González-García), wlopez@uninorte.edu.co (W. López-Pérez), rhernandezj@uninorte.edu.co (R. González-Hernández). 1 Tel.: +57 5 3509547. some transition-metal atoms [9–13], but with other alternative dopants [14]. The origin of ferromagnetism in DMSs is difficult to iden- tify when doping conventional compound semiconductors with magnetic transition metals due to the magnetic nature of these dopants. The observed ferromagnetism may be produced because the magnetic elements usually suffer from the problems of precip- itates in the form of clusters or secondary phase formations in the host semiconductor [15,16]. In order to explain the origin of ferromagnetism in DMSs with magnetic transition-metal dopants [17–23], there have been stud- ies showing the existence of ferromagnetism in DMSs with 3d nonmagnetic dopants [24], such as, Cu-doped AlN [9], Ti-doped AlN [10], Cu-doped GaN [25], and Ti-doped GaN [26]. All of these studies suggest the probability of fabricating DMSs using non- magnetic dopants. There are few reports with 4d nonmagnetic dopants [27]. Only the structural and optical properties of 4d im- purities in GaN and ZnO have been theoretically considered thus far [28–30]. In particular, experimental or theoretical studies of magnetism and electronic structure of Ag-doped AlN in the crys- tallization wurtzite phase have yet to be conducted. In order to provide fundamental insight into the interaction of Ag with AlN host semiconductor, and how these interactions can produce an induced magnetism, in this paper we study the electronic struc- ture and possible ferromagnetic orderings in Ag x Al 1-x N (0 < x < 0.125) compounds within the density functional theory (DFT) framework. 0038-1098/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.ssc.2011.08.024