Controlling the Curie temperature in (Ga,Mn)As through location of the Fermi level within the impurity band

The ferromagnetic semiconductor (Ga,Mn)As has emerged as the most studied material for prototype applications in semiconductor spintronics. Because ferromagnetism in (Ga,Mn)As is hole-mediated, the nature of the hole states has direct and crucial bearing on its Curie temperature T C . It is vigorous...

Full description

Saved in:
Bibliographic Details
Published in:Nature materials 2012-02, Vol.11 (5), p.444-449
Main Authors: Dobrowolska, M., Tivakornsasithorn, K., Liu, X., Furdyna, J. K., Berciu, M., Yu, K. M., Walukiewicz, W.
Format: Article
Language:English
Subjects:
639/301/119/997
639/301/930/12
Biomaterials
Chemistry and Materials Science
Condensed Matter Physics
Curie temperature
Fermi level
Fermi surfaces
Ferromagnetism
Impurities
Ions
Materials Science
Nanotechnology
Optical and Electronic Materials
Physics
Position (location)
Prototypes
Semiconductors
Valence band
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The ferromagnetic semiconductor (Ga,Mn)As has emerged as the most studied material for prototype applications in semiconductor spintronics. Because ferromagnetism in (Ga,Mn)As is hole-mediated, the nature of the hole states has direct and crucial bearing on its Curie temperature T C . It is vigorously debated, however, whether holes in (Ga,Mn)As reside in the valence band or in an impurity band. Here we combine results of channelling experiments, which measure the concentrations both of Mn ions and of holes relevant to the ferromagnetic order, with magnetization, transport, and magneto-optical data to address this issue. Taken together, these measurements provide strong evidence that it is the location of the Fermi level within the impurity band that determines T C through determining the degree of hole localization. This finding differs drastically from the often accepted view that T C is controlled by valence band holes, thus opening new avenues for achieving higher values of T C . Although (Ga,Mn)As is considered the model ferromagnetic semiconductor, the electronic structure of the charges — holes in this case — and its connection with the Curie temperature ( T C ) are still unclear. Experiments now provide a direct link between T C and the existence of an impurity band for the holes. Clarifying this issue is essential to designing other materials with potentially higher T C .
ISSN:1476-1122
1476-4660
DOI:10.1038/nmat3250