Semiconductor-baaed magneto-photonic crystals and their applications

我们成功地生长了一种新的四元合金磁性半导体（InGaMn）As，并发现它具有T_c ~ 130K的铁磁性。在（InGaMn）As中，可以改变晶格常数和带隙，并且可以在晶格匹配的InP衬底上生长，因此与光通信器件具有良好的兼容性。最近，我们在mn -delta掺杂的GaAs/p-AlGaAs异质结构中实现了172-250K的高T_c，这是III-V基材料中报道的最高值。最近，我们发现了mn - δ掺杂GaAs/p-AlGaAs异质结构中存在巨大的平面霍尔效应，并阐明了其磁各向异性。这种新型磁量子异质结构在基础研究和“自旋电子学”的潜在应用方面非常有吸引力。最近，我们在GaMnAs/AlAs/InGaAs/AlAs/GaMnAs双势垒铁磁隧道结中首次观察到负TMR和TMR比值（随AlAs厚度的变化）的振荡。这是由于共振隧穿和TMR效应同时出现所致。在半导体异质结构中实现如此大的自旋相关隧穿，即通过隧穿从一个半导体层注入到另一个半导体层，是朝着未来自旋电子学迈出的非常重要的一步，其中人们试图在半导体器件中使用自旋自由度。本文采用500 ~ 800℃退火的方法制备了铁磁体(MnAs)/III-V半导体（GaAs）颗粒结构（以下简称GaAs: MnAs）。在退火过程中，在GaAs（或GaMnAs）基体中形成了直径为几nm的MnAs铁磁团簇，表现出超顺磁性行为。我们已经建立了制造工艺，并测量了磁光特性。此外，我们还制作了GaAs:MnAs夹在GaAs/AlAs分布式Bragg反射器（dbr）中，并通过在GaAs:MnAs磁层中使用多重干涉和光的局部化，显著增强了磁光效应。这种结构为基于III-V化合物半导体的自旋控制光子器件的应用提供了新的机会。最近，我们在GaAs:MnAs颗粒结构中发现了室温下高达600%的正磁阻，进一步的研究正在进行中。少

We have successfully grown a new quaternary alloy magnetic semiconductor (InGaMn)As, and have found that it is ferromagnetic with T_c〜130K. In (InGaMn)As, the lattice constant and the bandgap can be changed, and it can be grown on lattice-matched InP substrates, thus having good compatibility with optical communication devices. More recently, we have realized high T_c of 172-250K in Mn-delta-doped GaAs/p-AlGaAs heterostructures, which are the highest values ever reported in III-V based materials. Recently, we find out the giant planar Hall effect in Mn-delta-doped GaAs/p-AlGaAs heterostructures and clarified the magnetic anisotropy. Such new magnetic quantum heterostructures are very attractive in view of fundamental research as well as potential applications to "spintronics".Recently, we observed negative TMR and oscillations of the TMR ratio (with varying the AlAs thickness) in GaMnAs/AlAs/InGaAs/AlAs/GaMnAs double-barrier ferromagnetic tunnel junctions, for the first time in magneti … More c semiconductor systems. This is caused by the appearance of resonant tunneling and TMR effects at the same time. Realization of such large spin-dependent tunneling in semiconductor heterostructures, that is spin injection from one semiconductor layer to another semiconductor layer via tunneling, is an very significant step towards future spintronics, in which one tries to use the spin degree of freedom in semiconductor devices.We have fabricated ferromagnet(MnAs)/III-V semiconductor(GaAs) granular structures, hereafter GaAs : MnAs, by annealing (GaMn)As at 500-800℃. During the annealing process, MnAs ferromagnetic clusters with diameters of a few nm were formed in a matrix of GaAs (or GaMnAs), exhibiting a superparamagnetic behavior. We have established the fabrication process and have measured magneto-optic properties. Furthermore, we have fabricated GaAs:MnAs sandwiched by GaAs/AlAs distributed Bragg Reflectors (DBRs), and have showed significant enhancement of magneto-optical effect by using multiple interference and localization of light in the GaAs:MnAs magnetic layer. This structure offers new opportunity for the application to spin-controlled photonic devices based on III-V compound semiconductors. Recently, we have found extremely large positive magnetoresistance of 600 % at room temperature in the GaAs:MnAs granular structures, and further investigations are underway. Less