Ferromagnetic superexchange in Cr-based diluted magnetic semiconductors

Blinowski, J.; Kacman, P.; Majewski, Jacek

doi:10.1103/physrevb.53.9524

Cited by 148 publications

(96 citation statements)

References 19 publications

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“…It is now well established that in the absence of free carriers the dominant exchange mechanism is the short-range superexchange in zinc-blende magnetic semiconductors. This mechanism leads to antiferromagnetic interactions, except perhaps for some Crand V-based compounds, for which the presence of a ferromagnetic coupling is theoretically predicted [74,75]. Remarkably, owing to the large exchange energy |βN 0 | and the high density of states, the hole-mediated longrange ferromagnetic exchange interaction can overcome antiferromagnetic superexchange [26]).…”

Section: Theoretical Description Of Mn-based Ferromagnetic Semiconducmentioning

confidence: 99%

“…With no doubt, the availability of intrinsic and n-type tetrahedrally-coordinated ferromagnetic compounds would enlarge considerably the impact of semiconductor electronics. Actually, a theoretical suggestion has been made [74,75] that superexchange in Cr-based and V-based II-VI compounds can lead to a ferromagnetic order. Desired material properties, such as divergent magnetic susceptibility and spontaneous magnetization, can also be achieved in the case of a strong antiferromagnetic super-exchange interaction.…”

Section: Beyond Mn-based Compoundsmentioning

confidence: 99%

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Ferromagnetic Semiconductors

2012

Semiconductor Spintronics

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The current status and prospects of research on ferromagnetism in semiconductors are reviewed. The question of the origin of ferromagnetism in europium chalcogenides, chromium spinels and, particularly, in diluted magnetic semiconductors is addressed. The nature of electronic states derived from 3d of magnetic impurities is discussed in some details. Results of a quantitative comparison between experimental and theoretical results, notably for Mn-based III-V and II-VI compounds, are presented. This comparison demonstrates that the current theory of the exchange interactions mediated by holes in the valence band describes correctly the values of Curie temperatures T C , magnetic anisotropy, domain structure, and magnetic circular dichroism. On this basis, chemical trends are examined and show to lead to the prediction of semiconductor systems with T C that may exceed room temperature, an expectation that are being confirmed by recent findings. Results for materials containing magnetic ions other than Mn are also presented emphasizing that the double exchange involving hoping through d states may operate in those systems.

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Section: Theoretical Description Of Mn-based Ferromagnetic Semiconducmentioning

confidence: 99%

Section: Beyond Mn-based Compoundsmentioning

confidence: 99%

Ferromagnetic Semiconductors

2012

Semiconductor Spintronics

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“…Search for the ferromagnetic transition has been successful in the case of Mn-based p-type IV-VI [2] and III-V compounds [3], in the latter case a critical temperature as high as 110 K has recently been reported for Ga 0.95 Mn 0.05 As [4,5]. In the case of II-VI DMS, a tight binding model [6] suggests that the superexchange in Cr-based DMS might be dominated by a ferromagnetic contribution. Accordingly, an attempt has been undertaken [7] to overcome the well-known small solubility of Cr in II-VI compounds by means of MBE growth of Cd 1−x Cr x Te.…”

Section: Introductionmentioning

confidence: 99%

“…, where effective spin concentrationxN o < xN o and temperature T + T o > T account for the influence of antiferromagnetic superexchange interactions [1,6,17].…”

Section: Introductionmentioning

confidence: 99%

Ferromagnetic Transition in Diluted Magnetic Semiconductors

Dietl¹

1999

Condens. Matter Phys.

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A summary is given of recent theoretical works on effects of the RudermanKittel-Kasuya-Yosida (RKKY) interaction between the localized spins in various dimensionality systems of doped diluted magnetic semiconductors (DMS). Since this interaction is long-range, its influence on the temperature and magnetic field dependencies of magnetization and spin splitting of the bands is evaluated in the mean field approximation, but by taking into consideration disorder-modified carrier-carrier interactions. Theoretical evaluations show that the hole densities, which can presently be achieved, are sufficiently high to drive a paramagneticferromagnetic phase transition in bulk and modulation-doped structures of II-VI DMS. The results of recent magnetooptical studies on MBE-grown samples, containing a single, modulation-doped, 8 nm quantum well of Cd 1−x Mn x Te/Cd 1−y−z Mg y Zn z Te:N are shown to corroborate the theoretical expectations. These studies reveal the presence of a ferromagnetic transition induced by the two-dimensional hole gas. The transition occurs between 1.8 and 2.5 K, depending on the Mn concentration x, in agreement with the theoretical model.

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“…A search for the ferromagnetic transition has been successful in the case of Mn-based p-type IV-VI [46] and IlI-V compounds [47], in the latter case a critical temperature as high as 110 K has recently been reported for Ga 0.95 Mn 0.05 As [48,49]. In the case of Il-VI semimagnetic semiconductors, a tight binding model [50] 8uggests that the superexchange in Cr-based semimagnetic semiconductors might be dominated by a ferromagnetic contribution. Accordingly, an attempt has been undertaken [51] …”

Section: Ferromagnetic Transition Induced By Free Carriersmentioning

confidence: 99%

From Magnetic Polarons to Ferromagnetism

Dietl

1998

Acta Phys. Pol. A

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A brief overview is given on selected effects of the exchange coupling between effective mass electrons and localized spins in II-VI semiconductors containing Mn ions. In the case of a carrier or exciton trapped by an impurity or defect, the exchange interaction leads to zero-field spin-splitting.The current theory of such complexes, known as bound magnetic polarons, describes correctly their spectroscopic and thermodynamic properties as well as their formation dynamics. At the same time, a free magnetic polarona delocalized carrier accompanied by a traveling clond of polarized spinsis not expected to exist for the actual values of the coupling constants. However, hołe scattering by thermodynamic and static fluctuations is shown to affect significantly its energy. For a strong coupling, the corresponding renormalization has to be described by a non-perturbative approach. Finally, the influence of the carrier liquid upon the Mn spins is discussed. Here, either optical pumping or p-type doping may lead to a ferromagnetic order, both in bulk and layered structures. Because of a long-range character of the carrier mediated interactions, this ordering is not destroyed by the fluctuations, even in the reduced dimensionality systems.

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Ferromagnetic superexchange in Cr-based diluted magnetic semiconductors

Cited by 148 publications

References 19 publications

Ferromagnetic Semiconductors

Ferromagnetic Semiconductors

Ferromagnetic Transition in Diluted Magnetic Semiconductors

From Magnetic Polarons to Ferromagnetism

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