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Growth and Characterization of Diluted Magnetic III-V Compound Semiconductors

稀磁 III-V 化合物半导体的生长和表征

基本信息

批准号：
02452142
负责人：
OHNO Hideo
金额：
$ 4.54万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

Molecular beam epitaxial (MBE) growth and electric and magnetic properties of diluted magnetic III-V semiconductors, especially (In, Mn) As, are studied. Following is a summary of the research results. Molecular Beam Epitaxial Growth : Maximum Mn concentration that can be incorporated into InAs lattice without having second phase (which is MnAs) is critically dependent on the growth temperature during MBE growth. At 300ﾟC, x (in In_<1-x>Mn_xAs) has to be<0.03 and the conduction is p-type whereas at 200ﾟC, x<0.25 and n-type.Characterization of Epitaxial layers : (1) Magnetism All n-type samples are paramagnetic and the direct interaction between Mn ions is antiferromagnetic with nearest neighbor J of -1.6 K. All p-type samples are paramagnetic at medium to high temperatures, but show spontaneous magnetization at low temperatures. Paramagnetic component which saturates only at high magnetic fields (4 to 9 T) is also present. The spontaneous magnetization makes up for 25 % of saturation m … More agnetization at the lowest temperature (1.4K) investigated. (2) Electrical Properties n-type samples show negative magnetoresistance at low temperatures. No hysteresis is observed. The Hall resistance of p-type samples is dominated by anomalous Hall effect. At temperatures below 7.5 K, hysteresis appears in B dependence of Hall resistance together with negative magnetoresistance extending to high magnetic fields. Hysteresis is only observed in p-type samples. This can be explained by the presence of large magnetic polarons with canted spins inside. The origin of the canting is believed to be the exchange interaction between holes and Mn ions. The interaction is mostly ferromagnetic with spin texture (i. e. canting) due to spin-orbit interaction of to Mn-Mn antiferromagnetic interaction. Rotation of polarons gives rise to the spontaneous magnetization, whereas the alignment of spins with high magnetic fields results in paramagnetic response at high fields. This is the first observation of weak ferromagnetism due to localized carrier-spin exchange in diluted magnetic semiconductors. Less

研究了稀磁性 III-V 半导体，特别是 (In, Mn) As 的分子束外延 (MBE) 生长以及电学和磁学性质。以下是研究结果的总结。分子束外延生长：在没有第二相（MnAs）的情况下，可以纳入 InAs 晶格的最大 Mn 浓度主要取决于 MBE 生长期间的生长温度。在 300°C 时，x（In_<1-x>Mn_xAs）必须<0.03，导电为 p 型，而在 200°C 时，x<0.25 且为 n 型。外延层的表征： (1) 磁性所有 n 型样品都是顺磁性，Mn 离子之间的直接相互作用是反铁磁性的，其最近邻 J 为 -1.6 K。所有 p 型样品在中高温下都是顺磁性的，但在低温下表现出自发磁化。还存在仅在高磁场（4 至 9 T）下饱和的顺磁性成分。在研究的最低温度 (1.4K) 下，自发磁化强度占饱和磁化强度的 25%。 (2)电性能n型样品在低温下表现出负磁阻。没有观察到滞后现象。 p型样品的霍尔电阻主要由反常霍尔效应决定。在低于 7.5 K 的温度下，霍尔电阻的 B 依赖性以及延伸至高磁场的负磁阻会出现磁滞现象。仅在 p 型样品中观察到滞后现象。这可以通过内部具有倾斜自旋的大磁极化子的存在来解释。倾斜的起源被认为是空穴和锰离子之间的交换相互作用。由于 Mn-Mn 反铁磁相互作用的自旋轨道相互作用，相互作用主要是具有自旋纹理（即倾斜）的铁磁相互作用。极化子的旋转引起自发磁化，而自旋与高磁场的对齐导致高磁场下的顺磁响应。这是由于稀释磁性半导体中的局域载流子自旋交换而首次观察到弱铁磁性。较少的