Successive spin polarization contribution to the magnetic coupling in diluted magnetic semiconductors: A quantitative verification

In this pedagogical paper, the comparative analysis of two common approaches describing the ferromagnetic phase transition in diluted magnetic semiconductors (DMS) is expounded in terms of the Weiss field approximation. Assuming a finite spin polarization of the magnetic ions, the treatment of carrier-ion exchange interaction in the first order evokes a homogeneous Weiss molecular field that polarizes the spins of free carriers. In turn, this spin polarization of the free carriers exerts the effective field that may stabilize the DMS spin polarization belowa critical temperature TC. The treatment of such self-consistent spontaneous DMS magnetization can be done in terms of the spin-spin interaction independent of the inter-ion distance and the infinitesimal in thermodynamic limit. On the other hand, by additionally accounting for the second-order effects of the carrier-ion exchange interaction, we can treat a Weiss field in terms of the Ruderman–Kittel–Kasuya–Yosida indirect spin-spin interaction, which oscillates and does not disappear at finite inter-ion distances in the case of a finite concentration of carriers. These both approaches result in the same Curie temperature TC provided a non-correlated homogeneous random distribution of the localized spin moments over the sample volume. We discuss the origin of such coincidence and show when this is not a case in other more realistic models of the conducting DMSs.

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Successive Spin-Correlated Local Processes Underlying the Magnetism in Diluted Magnetic Semiconductors and Related Magnetic Materials

Advances in Chemical and Materials Engineering - Computational Approaches to Materials Design ◽

10.4018/978-1-5225-0290-6.ch002 ◽

2016 ◽

pp. 13-27

Author(s):

Antonis N. Andriotis ◽

Madhu Menon

Keyword(s):

Transition Metal ◽

Metal Oxides ◽

Spin Polarization ◽

Transition Metal Oxides ◽

Diluted Magnetic Semiconductors ◽

Magnetic Semiconductors ◽

Nearest Neighbors ◽

Synergistic Action ◽

Superexchange Coupling ◽

Diluted Magnetic

Recent works have suggested that the defect induced magnetism in Diluted Magnetic Semiconductors (DMSs), Transition Metal Oxides (TMOs) and related materials is facilitated and enhanced by codoping and the synergistic action between the codopants. In the present work we demonstrate that the proposed defect synergy is the result of the interplay among correlated spin-polarization processes which take place in a successive way in neighborhoods centered at the codopants and include their first nearest neighbors. These processes result in a reduction in the superexchange coupling which in turn causes an enhancement in the ferromagnetic coupling (FMC) among the magnetic dopants. The proposed FMC is demonstrated using ab initio calculations of the electronic properties of codoped ZnO, GaN and TiO2.

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Electric Field Controlled Itinerant Carrier Spin Polarization in Ferromagnetic Semiconductors

Advances in Condensed Matter Physics ◽

10.1155/2021/6663876 ◽

2021 ◽

Vol 2021 ◽

pp. 1-5

Author(s):

Gezahegn Assefa

Keyword(s):

Electric Field ◽

Spin Polarization ◽

Diluted Magnetic Semiconductors ◽

Magnetic Semiconductors ◽

Ferromagnetic Semiconductors ◽

Ferromagnetic Metals ◽

Spin Dependent Transport ◽

Diluted Magnetic ◽

Dependent Transport ◽

Electrical Manipulation

Electric field control of magnetic properties has been achieved across a number of different material systems. In diluted magnetic semiconductors (DMSs), ferromagnetic metals, multiferroics, etc., electrical manipulation of magnetism has been observed. Here, we study the effect of an electric field on the carrier spin polarization in DMSs ( GaAsMn ); in particular, emphasis is given to spin-dependent transport phenomena. In our system, the interaction between the carriers and the localized spins in the presence of electric field is taken as the main interaction. Our results show that the electric field plays a major role on the spin polarization of carriers in the system. This is important for spintronics application.

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Transport Properties of (Ga,Mn)As Diluted Magnetic Semiconductors in the Bulk and in Layered Systems

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.52.1 ◽

2006 ◽

Vol 52 ◽

pp. 1-10 ◽

Cited By ~ 3

Author(s):

Ilja Turek ◽

K. Carva ◽

J. Kudrnovsky

Keyword(s):

Electronic Structure ◽

Transport Properties ◽

Spin Polarization ◽

Diluted Magnetic Semiconductors ◽

Magnetic Semiconductors ◽

Tight Binding ◽

Linear Response Theory ◽

Local Spin Density Approximation ◽

Lmto Method ◽

Diluted Magnetic

Transport properties of systems based on diluted magnetic semiconductors (Ga,Mn)As are investigated theoretically by means of the Kubo linear response theory. The underlying electronic structure is obtained within the local spin-density approximation using the scalarrelativistic tight-binding linear muffin-tin orbital (TB-LMTO) method. The effect of substitutional randomness on the electronic structure and on the transport properties is systematically described in the coherent potential approximation (CPA). The quantities studied include the residual resistivities of the bulk alloys as well as conductances of epitaxial trilayers Cr/(Ga,Mn)As/Cr (001) in the current-perpendicular-to-plane (CPP) orientation. The results witness that various compensating defects such as As antisite atoms and Mn interstitials have much stronger detrimental effect on the spin polarization of the CPP conductances as compared to their influence on the spin polarization of the bulk conductivities.

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Temperature dependent magnetization of the two band model for diluted magnetic semiconductors

Communications in Physics ◽

10.15625/0868-3166/24/2/4043 ◽

2014 ◽

Vol 24 (2) ◽

pp. 141

Author(s):

Vu Kim Thai ◽

Hoang Anh Tuan

Keyword(s):

Diluted Magnetic Semiconductors ◽

Magnetic Semiconductors ◽

Magnetic Coupling ◽

Band Model ◽

Coupling Constant ◽

Temperature Dependent ◽

Impurity Bands ◽

Diluted Magnetic ◽

Two Band Model ◽

Temperature Dependent Magnetization

The temperature dependent magnetization of a two band model for diluted magnetic semiconductors as a function of magnetic coupling constant, hopping parameters and carrier densities is calculated by using the coherent potential approximation. It is shown that the degree of overlapping of the impurity bands and carrier density are crucial parameters determining the magnetization behavior of the system.

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