Carrier‐mediated stabilization of ferromagnetism in semiconductors: holes and electrons

Dalpian, Gustavo M.; Wei, Su‐Huai

doi:10.1002/pssb.200666809

Cited by 50 publications

(37 citation statements)

References 61 publications

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“…As a consequence, the FM stability is enhanced. This is in good agreement with the viewpoint in the reference [43], where the authors pointed out that it is necessary first to increase the exchange splitting of the conduction band for electron-mediated ferromagnetism. This can be explained by the fact that S vacancy acts as a donor since the removing of one S atom brings two additional electrons.…”

Section: Resultssupporting

confidence: 86%

Electronic structures and magnetic properties in Ti-doped ZnS

Chen

Yang

et al. 2015

Solid State Communications

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Section: Resultssupporting

confidence: 86%

Electronic structures and magnetic properties in Ti-doped ZnS

Chen

Yang

et al. 2015

Solid State Communications

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“…From the electronic structure calculations for Mn-doped ZnO, it was suggested that bulk (Zn,Mn)O becomes ferromagnetic when the majority t a states of the Mn ions are partially occupied [12]. The details of the carrier-mediated ferromagnetism were later discussed, based on level repulsions between the Mn d orbitals and the host p orbitals [13,14]. For bulk (Zn,Mn)O, previous first-principles density functional calculations showed that ferromagnetism can be induced by additional p-type doping using N and Li acceptors [15e21], while an antiferromagnetic (AFM) ordering is more favorable in undoped and n-type samples.…”

Section: Introductionmentioning

confidence: 99%

Hole doping effect on ferromagnetism in Mn-doped ZnO nanowires

Tsogbadrakh¹,

Choi²,

Lee³

et al. 2011

Current Applied Physics

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“…Partial occupation of the empty minority t 2d states will result in a transition to FM ordering through the energy gained from the filling of the bonding state. Within such a band coupling model [16,17], the energy difference between the FM and AFM phases can be described as where m e is the additional number of electrons per Co(II) ion and 2 dd and 1;2 dd are the direct exchange and superexchange parameters, respectively (Fig. 1). FIG.…”

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confidence: 99%

Theoretical Description of Carrier Mediated Magnetism in Cobalt Doped ZnO

2008

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Substitutional cobalt in ZnO has a weak preference for antiferromagnetic ordering. Stabilization of ferromagnetism is achieved through n-type doping, which can be understood through a band coupling model. However, the description of the transition to a ferromagnetic ground state varies within different levels of band theory; issues arise due to the density functional theory underestimation of the band gap of ZnO, and the relative position of the nominally unfilled Co t 2d states. We examine these limitations, including approaches to overcome them, and explain the contradictions in previous studies, which drastically overestimate the doping threshold for magnetic ordering. DOI: 10.1103/PhysRevLett.100.256401 PACS numbers: 71.20.Nr, 71.15.Mb, 75.10.ÿb, 75.50.Pp The potential to simultaneously tune both charge and spin in solid state materials has lead to great interest in the field of spintronics [1]. The ultimate aim is a controllable room temperature semiconducting ferromagnet, which could be used in magnetoelectric and magnetotransport devices. Intrinsically magnetic semiconductors generally possess relatively low Curie temperatures (T C ); however, it has been proposed that incorporating transition metal or rare earth ions into a nonmagnetic semiconductor host lattice, forming a dilute magnetic semiconductor (DMS), may help raise T C above room temperature [2,3].In DMS materials, magnetism is influenced and controlled by the presence of charge carriers in the form of holes (GaAs:Mn) or electrons (GaN:Gd). There is still great debate over the fundamental mechanism behind the origin of the observed high temperature magnetic alignment in many of these systems. The situation is not helped by large variation in both experimental and theoretical studies [4 -8].Cobalt doped ZnO has become a focus of attention due to its reported high T C of up to 700 K and, most promisingly, the reversible cycling of FM ordering [9]. Coupled with existing optical and electrical properties of ZnO, the addition of controllable magnetism could make it a technologically essential material. It has been reported that at Co concentrations of less than 10%, the solubility is good and Co occupies a substitutional Zn site in a 2 charge state [9,10]. B . The splitting between filled e d and empty minority t 2d states for tetrahedral Co is typically on the order of 1.5-2 eV [12]. In a wide gap semiconductor such as ZnO (E g 3:4 eV), this would place the minority spin Co t 2d states within the band gap, as has been reported from both optical and magnetic measurements for ZnO:Co [13][14][15]. Surprisingly, this is not the case in previous theoretical studies [5][6][7][8].From consideration of Co 3d band coupling, FM interactions between occupied majority t 2d states results in no net energy gain due to filled bonding and antibonding combinations, while AFM interactions can result in a small energy gain (Fig. 1). Partial occupation of the empty minority t 2d states will result in a transition to FM ordering through the energy gained from the fi...

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Carrier‐mediated stabilization of ferromagnetism in semiconductors: holes and electrons

Cited by 50 publications

References 61 publications

Electronic structures and magnetic properties in Ti-doped ZnS

Electronic structures and magnetic properties in Ti-doped ZnS

Hole doping effect on ferromagnetism in Mn-doped ZnO nanowires

Theoretical Description of Carrier Mediated Magnetism in Cobalt Doped ZnO

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