High-Curie-temperature Ga1−xMnxAs obtained by resistance-monitored annealing

Edmonds, K. W.; Wang, K. Y.; Campion, R. P.; Neumann, Alexander; Farley, N. R. S.; Gallagher, B. L.; Foxon, C.T.

doi:10.1063/1.1529079

Cited by 328 publications

(269 citation statements)

References 16 publications

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“…The common trends in annealing (at temperatures close to the growth temperature) suggest the presence of competing mechanisms. One mechanism yields the increase of T C and is ascribed in a number of reports to the removal of charge and moment compensating interstitial Mn impurities 57,58 . The removal is slowed down by the growth of an oxide surface layer during annealing 54 and an additional mechanism can eventually yield reduction of T C after sufficiently long annealing times, depending on the annealing temperature.…”

Section: Methodsmentioning

confidence: 99%

The essential role of carefully optimized synthesis for elucidating intrinsic material properties of (Ga,Mn)As

et al. 2013

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(Ga,Mn)As is at the forefront of spintronics research exploring the synergy of ferromagnetism with the physics and the technology of semiconductors. However, the electronic structure of this model spintronics material has been debated and the systematic and reproducible control of the basic micromagnetic parameters and semiconducting doping trends has not been established. Here we show that seemingly small departures from the individually optimized synthesis protocols yield non-systematic doping trends, extrinsic charge and moment compensation, and inhomogeneities that conceal intrinsic properties of (Ga,Mn)As. On the other hand, we demonstrate reproducible, well controlled and microscopically understood semiconducting doping trends and micromagnetic parameters in our series of carefully optimized epilayers. Hand-in-hand with the optimization of the material synthesis, we have developed experimental capabilities based on the magneto-optical pumpand-probe method that allowed us to simultaneously determine the magnetic anisotropy, Gilbert damping and spin stiffness constants from one consistent set of measured data.

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Section: Methodsmentioning

confidence: 99%

The essential role of carefully optimized synthesis for elucidating intrinsic material properties of (Ga,Mn)As

et al. 2013

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“…The charge and moment compensation after annealing is not significant for our samples and the moment per x s or x ef f is around ϳ4 B -4.5 B . This corresponds within the error bars to the 5 B contribution of the S = 5 2 local Mn Ga moment and ϳ͑−0.25͒ -͑−0.5͒ B contribution of the antiferromagnetically coupled valence-band hole 25 in collinear ͑Ga,Mn͒As ferromagnets. In the inset of Fig.…”

Section: T C Vs Mn Ga Effective Mn Ga and Hole Densitiesmentioning

confidence: 99%

“…It is now established that the success has been made possible by the technological progress in controlling crystallographic quality of the materials, namely, in reducing the number of unintentional charge and moment compensating defects through optimized growth and post-growth annealing procedures. [3][4][5][6][7][8][9][10] Experiments also suggest that the general picture of ferromagnetism that applies to these metallic ͑Ga,Mn͒As systems is the one in which magnetic coupling between local Mn moments is mediated by delocalized holes in the ͑Ga,Mn͒As valence band. The fact that the mechanism does not imply a fundamental T c limit below room temperature motivates a detailed analysis of our understanding of the T c trends in currently available high quality metallic materials with Mn doping ranging from approximately 2% to 9%.…”

Section: Introductionmentioning

confidence: 99%

“…[5][6][7][8][9] The maximum T c = 173 K reported 9 to date is likely another short-lived record in bulk ͑Ga,Mn͒As ferromagnets. It is now established that the success has been made possible by the technological progress in controlling crystallographic quality of the materials, namely, in reducing the number of unintentional charge and moment compensating defects through optimized growth and post-growth annealing procedures.…”

Section: Introductionmentioning

confidence: 99%

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Prospects for high temperature ferromagnetism in (Ga,Mn)As semiconductors

et al. 2005

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We report on a comprehensive combined experimental and theoretical study of Curie temperature trends in ͑Ga,Mn͒As ferromagnetic semiconductors. Broad agreement between theoretical expectations and measured data allows us to conclude that T c in high-quality metallic samples increases linearly with the number of uncompensated local moments on Mn Ga acceptors, with no sign of saturation. Room temperature ferromagnetism is expected for a 10% concentration of these local moments. Our magnetotransport and magnetization data are consistent with the picture in which Mn impurities incorporated during growth at interstitial Mn I positions act as double-donors and compensate neighboring Mn Ga local moments because of strong nearneighbor Mn Ga u Mn I antiferromagnetic coupling. These defects can be efficiently removed by post-growth annealing. Our analysis suggests that there is no fundamental obstacle to substitutional Mn Ga doping in high-quality materials beyond our current maximum level of 6.8%, although this achievement will require further advances in growth condition control. Modest charge compensation does not limit the maximum Curie temperature possible in ferromagnetic semiconductors based on ͑Ga,Mn͒As.

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“…Other experimental studies (often using careful sample annealing procedures) do not find such reentrant metalinsulator transition behavior. 12,13 It is important to emphasize that the existence of DMS ferromagnetism seems to be independent of the system being metallic or insulating. For GaMnAs, both metallic and insulating samples are ferromagnetic with the transition temperature typically being higher for metallic systems although this may not necessarily be a generic behavior.…”

Section: Introductionmentioning

confidence: 99%

How to make semiconductors ferromagnetic: a first course on spintronics

Sarma

Hwang

Kaminski

2003

Solid State Communications

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The rapidly developing field of ferromagnetism in diluted magnetic semiconductors, where a semiconductor host is magnetically doped by transition metal impurities to produce a ferromagnetic semiconductor (e.g. Ga1−xMnxAs with x ≈ 1 − 10%), is discussed with the emphasis on elucidating the physical mechanisms underlying the magnetic properties. Recent key developments are summarized with critical discussions of the roles of disorder, localization, band structure, defects, and the choice of materials in producing good magnetic quality and high Curie temperature. The correlation between magnetic and transport properties is argued to be a crucial ingredient in developing a full understanding of the properties of ferromagnetic semiconductors.

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High-Curie-temperature Ga1−xMnxAs obtained by resistance-monitored annealing

Cited by 328 publications

References 16 publications

The essential role of carefully optimized synthesis for elucidating intrinsic material properties of (Ga,Mn)As

The essential role of carefully optimized synthesis for elucidating intrinsic material properties of (Ga,Mn)As

Prospects for high temperature ferromagnetism in (Ga,Mn)As semiconductors

How to make semiconductors ferromagnetic: a first course on spintronics

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