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Carrier induced ferromagnetism and its control in III-V diluted magnetic semiconductors

III-V族稀磁半导体中的载流子感应铁磁性及其控制

基本信息

批准号：
08455002
负责人：
OHNO Hideo
金额：
$ 4.8万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

项目摘要

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.

本研究的目的是阐明磁性与载流子浓度等半导体性质之间的关系，并探索使用III-V族稀磁半导体量子结构通过控制载流子浓度来控制磁性的可能性。本文主要研究了（Ga，Mn）As的铁磁转变温度（T_c）和空穴浓度（p）与Mn浓度（x）的关系，并对（Ga，Mn）As的铁磁转变温度（T_c）和空穴浓度（p）与Mn浓度（x）的关系进行了研究。结果表明，T_c和p都随x的增加而单调增加，直到x = 0.05。当x= 0.053时，最高的T_c为110 K。2.实现了所有基于超导体的铁磁/非磁量子结构，（Ga，Mn）As/（Al，Ga）As异质结构。即使在（Ga，Mn）As层厚度小于10 nm的结构中，铁磁有序性也被破坏了。3.通过对顺磁区磁电阻的分析，确定了磁自旋与空穴之间的交换相互作用（J_）的大小<pd>。这一J_<pd>c足够大，可以用RKKY公式很好地解释T_c，这些结果有力地表明，利用场效应晶体管结构，通过电场改变层中载流子浓度来控制（Ga，Mn）As的磁性是可能的。