Prediction of Half-Metallic Ferromagnetism in Cu- and K-Doped MgS: A Comparative Study
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ORIGINAL PAPER
Prediction of Half-Metallic Ferromagnetism in Cu- and K-Doped MgS: A Comparative Study W. Adli 1 Received: 2 May 2020 / Accepted: 28 May 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Ab initio calculations based on density functional theory have been used to comparatively investigate the electronic and magnetic properties of two non-magnetic ions (Cu, K)-doped magnesium sulfide. The results obtained indicate that the ferromagnetic phase is always energetically favorable than the paramagnetic one. It is also found that these ternary alloys are half-metallic ferromagnets with a total magnetic moment of 1.00 μB per supercell. The ferromagnetism is induced by hybridization between Cu 3d and its nearest neighboring S 3p in Cu-doped MgS, while it originates in the spin polarization of the p shell of anions S in K-doped MgS. Our results make these compounds attractive materials for possible spintronics devices. Keywords Diluted magnetic semiconductor . Half-metallic ferromagnetism . p-d hybridization . p-electron ferromagnetism
1 Introduction Diluted magnetic semiconductors (DMSs) have been extensively studied due to their potential applications in the field of spintronics [1–3]. In particular, half metallic DMSs are attracting a considerable amount of attention, for which only one of the two spin channels presents a gap at the Fermi level (EF), while the other has a metallic character, leading 100% carrier spin polarization at EF. For practical microelectronic device applications, half metallic (HM) ferromagnets should exhibit ferromagnetism at room or higher temperatures [4]. During the past years, significant research efforts have been made toward studying the room temperature ferromagnetism in transition metal (TM)-doped II–VI and III–V semiconductors [5–13]. However, the origin of ferromagnetism in these alloys continues to be a subject of debate. This is because the TM-doped semiconductors usually suffer from the problems of the precipitates or secondary phase formation [14, 15]. To avoid these controversies, many research works have been focused on investigating the ferromagnetism of the intrinsic nonmagnetic element-doped semiconductors, such as Cu-
* W. Adli [email protected] 1
Département de Génie Physique, Faculté de Physique, Université des Sciences et de la Technologie d’Oran (USTO), BP 1505 El-M’naouer, 31000 Oran, Algeria
doped ZnO [16, 17], GaN [18], and AlN [19, 20]. Besides Cu, other intrinsic nonmagnetic elements, like K, C, and Sr, can also lead to ferromagnetism in AlN [21], ZnO [22, 23], and III–V [24], respectively. More interestingly, most of these studies indicate the possibility of fabricating the room temperature ferromagnets, which provide an opportunity to study new mechanisms of ferromagnetism and open new ways to find advanced spintronic materials. Due to their wide band gaps and low dielectric constants, the magnesium chalcogenides, MgX (X = S, Se, and Te) have received enormous interest from both experimental and theoretical point
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