| Co-Investigator(Kenkyū-buntansha) |
OHNO Yuzo TOHOKU UNIVERSITY, Research Institute of Electrical Communication, Tohoku Univer, 電気通信研究所, 助手 (00282012)
MATSUKURA Fumihiro TOHOKU UNIVERSITY, Research Institute of Electrical Communication, Tohoku Univer, 電気通信研究所, 助手 (50261574)
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| Research Abstract |
The purpose of this research is to clarify the relationship between magnetism and semiconductor properties such as carrier concentration, and to explore the possibility of control of magnetism by the control of carrier concentration, using III-V based diluted magnetic semiconductor quantum structures. Here, we concentrated mainly on (Ga, Mn) As which we showed earlier that it can be grown by lowtemperature molecular-beam epitaxy and shows hole-induced ferromagnetic order at low temperaturcs.
The summary of results is as follows ;
1.From magnetotransport measuremens, the dependence of ferromagnetic transition temperature (T_c) and hole concentration (p) of (Ga, Mn) As on the Mn concentration (x) was determined. It is showm that both T_c and p monotonically increase with increase of x up to about 0.05. The highest T_c obtained so far is 110 K for a sample with x=0.053.
2.All semiconductor-based ferromagnetic/non-magnetic quantum structures, (Ga, Mn) As/(Al, Ga) As heterostructures were realized. Even in such structures, where the thickness of (Ga, Mn) As layrs is below 10 nm, the ferromagnetic order is preserved.
3.From the analysis of the magnetoresistance in the paramagnetic region, the magnitude of exchange interaction (J_<pd>) between magnetic spins and holes was determined. This J_<pd> is shown to be large enough to explain the observed T_c by the well RKKY formula remarkably well.
These results strongly indicates that it is possible to control the magnetism of (Ga, Mn) As by changing the carrier concentration of the layrs by electric fields using field effect transistor structures.
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