Successive spin polarizations underlying a new magnetic coupling contribution in diluted magnetic semiconductors

Abstract

We propose a new type of magnetic coupling (MC) that is found in diluted magnetic semiconductors (DMSs). The origin of this is found to be the result of charge transfer processes followed by successive spin polarizations (SSPs) along successive cation-anion segments which include the impurities. The basic process underlying the SSP-based MC (SSP-MC) is the sharing of a single spin orbital by two neighboring impurities. As such, it can be considered as a localized double exchange as it is not mediated by free carriers. SSP-MC can be either ferromagnetic (SSP-FMC) or antiferromagnetic (SSP-AFMC) and, as demonstrated here, the SSP-FMC can be significantly enhanced via codoping; it can act in competition with superexchange and/or double and/or p-d exchange interactions. While the SSP-MC is not directly related to the magnitude of the magnetic moments of the impurities, it depends strongly on the energy difference of the host and impurity d-band centers, the difference of their electronegativities and rather weakly on the coupling interactions between them as well as between the cations and their mediating anions. The validity of the proposed SSP-MC as a new type of magnetic coupling is demonstrated by ab initio results for DMSs, namely ZnO, GaN, GaP, TiO2 and MoS2 monodoped (with Co, Cu and Mn) and codoped (with Co-Cu-Co and Mn-Cu-Mn).

Formation of Fe–Fe Antiferromagnetic Dimers in Doped TiO2:Fe Nanoparticles

“…Three possible spin values of Fe 3+ ion S = 5/2, 2, and 1/2 corresponding to different spin states of Fe3+ and Fe2+ ions were tested. Moreover, charge transfer processes can affect the value of Fe magnetic moment reducing it down to 2.8 μ B /Fe, as it was shown in refs − . However, adjustment of the spin value for Fe ions when using a model of purely paramagnetic state and Brillouin function approach gives poor quantitative description of the magnetic measurements data for all samples, as we demonstrated in this study.…”

Dependence of the magnetic interactions in MoS2 monolayer on Mn-doping configurations

“…More recently, another origin of magnetic interaction among Mn impurities in MoS 2 ML has been proposed and called successive spin polarizations (SSP) [37,38]. The SSP magnetic coupling model is based on the spin-polarization induced by impurities in the host material to their nearest environment, i.e the closest atoms mainly [37][38][39][40].…”

“…More recently, another origin of magnetic interaction among Mn impurities in MoS 2 ML has been proposed and called successive spin polarizations (SSP) [37,38]. The SSP magnetic coupling model is based on the spin-polarization induced by impurities in the host material to their nearest environment, i.e the closest atoms mainly [37][38][39][40]. In particular, a specific Mn impurity dictates the spin polarization of its first Next Nearest neighbors (NN), namely Mo and S, which in return dictate the spin polarization of the NN possible dopant [37,38].…”

“…The SSP magnetic coupling model is based on the spin-polarization induced by impurities in the host material to their nearest environment, i.e the closest atoms mainly [37][38][39][40]. In particular, a specific Mn impurity dictates the spin polarization of its first Next Nearest neighbors (NN), namely Mo and S, which in return dictate the spin polarization of the NN possible dopant [37,38]. Unlike the double-exchange mechanism, the SSP FM coupling is based on localized electronic processes that take place between Mn impurities [37].…”

Coupled and Implicit Relationships of the d-Band Center of the Magnetic Dopants in Diluted Magnetic Semiconductors and Transition Metal Oxides

“…14 In addition to the use of d c -based models in the adsorption and binding properties, we have shown recently that d c is well correlated with the magnetic features of diluted magnetic semiconductors (DMSs) and transition metal oxides (TMOs). 15,16 Our search has led us to the identification of a new set of universal atomic and macroscopic factors which appear to underlie the development of the magnetic coupling (MC) in such diverse materials. Interestingly, these factors have been found to constitute a suitable set of descriptors which can be used to facilitate statistical predictive approaches to create a much larger subsidiary set of materials.…”