First-Principles Study on the Ferromagnetism of Mn-Doped LiZnAs Half-Heusler Compound
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AGNETISM
First-Principles Study on the Ferromagnetism of Mn-Doped LiZnAs Half-Heusler Compound M. Saidia, M. Belhadja, A. Zaouia, S. Kacimia, *, and A. Kadiria a Laboratoire
de Physique Computationnelle des Materiaux (LPCM), Universite DjillaliLiabes de Sidi Bel-Abbes, Sidi Bel-Abbes, 22000 Algeria * e-mail: [email protected] Received May 13, 2020; revised July 3, 2020; accepted July 7, 2020
Abstract—We have investigated the magnetic properties of Mn-doped LiZnAs half-Heusler compound using density functional simulations within the gradient generalized approximation (GGA) with the on-site Hubbard Ueff parameter (GGA+U). A detailed study of magnetism in the two compounds GaAs and LiZnAs doped with Mn is presented. A super-cell of 64 and 96 atoms have been built for the zinc blende and the halfHeusler compounds, respectively. GGA+U calculations predict that the ferromagnetic state in LiZnAs:Mn compound with a magnetic moment of 3.51 μB per manganese is more appropriate in energy than the antiferromagnetic state. The topological similarity between GaAs and LiZnAs non-magnetic compounds is also confirmed in these Mn-doped systems. The band structures and densities of states show that the Mn-doped half-Heusler LiZnAs has become a dilute magnetic semiconductor with a direct gap of 0.43 eV. The cubic symmetry and distances between the dopant pairs (Mn) are two key factors to predict the character and the magnetic order of Mn-doped LiZnAs system. Keywords: LAPW + LO, DFT+U, impurity defects, magnetic properties, ferromagnetic semiconductor DOI: 10.1134/S106378342011027X
1. INTRODUCTION Diluted magnetic semiconductors (DMS) have attracted a considerable attention because of their potential applications in spintronics area [1]. As promising materials for this field, III–V semiconductor-based compounds have been extensively studied [2]. (Ga, Mn)As is one of the spintronic materials based on III–V compounds, in which the Ga3+ ion is substituted by Mn2+, becoming a sp-type ferromagnetic where holes are introduced in ferromagnetic interactions [3]. However, the development of (Ga, Mn)As is limited by the low concentration of doping and by metastable specimens available only as thin films [4]. The other limit of this material is that the substitution of divalent atoms of Mn provides both local spins and holes, leading to the absence of independent control of local moments and of concentration carriers. To overcome these difficulties, several groups of researchers [5] proposed systems based on an I–II–V semiconductor such as LiZnAs compound, where the element of group III (Ga) in (Ga, Mn) As is simply substituted by another element of group I (Li) and of group II (Zn). The Mn2+ ions occupy the sites of Zn2+ that are bivalent, and a high solubility of Mn in the compound is observed [5]. The crystal structure and the band structure of LiZnAs are very similar to those of GaAs
[6, 7], which makes Li(Zn, Mn) a ferromagnetic system analogous to (Ga, Mn)As. Experimentally, Deng et al. [8–10] synthesized LiZn1 – xMnx system. They fou
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