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) 生长和电学和磁学特性，以下是研究结果的摘要：可以实现的最大 Mn 浓度。在没有第二相（MnAs）的情况下融入 InAs 晶格主要取决于 MBE 生长过程中的生长温度，在 300°C 时，x (in. In_<1-x>Mn_xAs) 必须<0.03，导电为 p 型，而在 200°C 时，x<0.25 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，最近邻 J 为 -1.6 K。所有 p 型样品在中到高时都是顺磁性的温度，但在低温下表现出自发磁化，也存在仅在高磁场（4 至 9 T）下饱和的顺磁性成分，自发磁化在最低温度（1.4K）下占饱和磁化的 25％。 (2) 电学特性 n 型样品在低温下表现出负磁阻，未观察到 p 型样品的霍尔电阻主要是反常霍尔效应。当温度低于 7.5 K 时，霍尔电阻的 B 依赖性以及延伸至高磁场的负磁阻仅在 p 型样品中观察到，这可以通过内部具有倾斜自旋的大磁极化子来解释。倾斜的起源被认为是空穴和 Mn 离子之间的交换相互作用，由于的自旋轨道相互作用，该相互作用主要是具有自旋结构（即倾斜）的铁磁性。 Mn-Mn 反铁磁相互作用。极化子的旋转引起自发磁化，而自旋与高磁场的排列导致高磁场下的顺磁响应，这是由于稀释中的局部载流子自旋交换而导致的弱铁磁性的首次观察。磁性半导体。更少