Local and Non-local Magnetic Moments in Semiconductors

这个个人研究者奖将为一个项目提供支持，该项目将研究在半导体中添加磁矩的影响。将制备掺杂磁性离子（如稀土元素和Mn）的非晶态Si、Ge和C，并测量其电子、磁性、热力学和结构性能。声子刚度和半导体带隙对这些特性的影响将被确定。这些增加的局部力矩与电子局域化时金属-绝缘体跃迁形成的自发力矩之间的相互作用将被研究。该研究将为三维金属-绝缘体转变的微观模型提供现象学基础，并了解在半导体中引入局部磁矩对输运和磁性的影响。该项目将为两名研究生和约5-6名本科生提供研究培训和教育，包括通过PI与加州大学圣地亚哥分校磁记录研究中心和两个国家实验室（国家高磁场实验室和洛斯阿拉莫斯实验室）的联系接触工业界。磁矩在许多材料中起着至关重要的作用（例如，高Tc超导体和巨磁阻锰钢）。众所周知，给半导体增加磁矩会产生非常大的效应，但这些效应还没有得到很好的理解。特别是，当这种材料被置于磁场中时，电阻的变化（磁电阻）可能是巨大的。这个项目将研究在半导体中加入磁矩的效果。将制备掺杂磁性离子如稀土元素和锰的非晶Si、Ge和C样品。它们的电子、磁性、热力学和结构性质将在很宽的温度、磁场和掺杂水平范围内进行测量。这项研究将试图确定控制非晶半导体中磁矩大效应的原理。对这些效应的进一步了解可能会为开发中的自旋电子技术指明使非常大的磁电阻使用的道路。此外，这项研究可能会增加我们对磁矩为什么在当前感兴趣的其他材料中发挥如此重要作用的理解。该项目将为两名研究生和约5-6名本科生提供研究培训和教育，包括通过PI的合作为他们提供接触工业和国家实验室的机会。因此，他们将为未来在学术界、工业或政府实验室的职业生涯做好充分的准备。

This individual investigator award will provide support for a project that will investigate the effect of adding magnetic moments to semiconductors. Amorphous Si, Ge, and C doped with magnetic ions such as rare earth elements and Mn will be prepared and their electronic, magnetic, thermodynamic, and structural properties measured. The influence of the phonon stiffness and the semiconductor band gap on these properties will be determined. The interaction between these added local moments and the spontaneous moments formed at the Metal-Insulator transition as electrons localize will be studied. The research will provide a phenomenological underpinning for a microscopic model for the three dimensional Metal-Insulator transition, and an understanding of the effect on both transport and magnetic properties of introducing local magnetic moments into a semiconductor. The project will provide research training and education for two graduate students and an estimated 5-6 undergraduates, including exposure to industry through the PI's connections with the Center for Magnetic Recording Research at UCSD and to two National Labs, the National High Magnetic Field Lab and Los Alamos.Magnetic moments play a crucial role in many materials (e.g. the high Tc superconductors and the colossal magnetoresistance manganites). It is known that adding magnetic moments to semiconductors produces effects that are extremely large, but these effects are not well understood. In particular the change in the electrical resistance when such a material is placed in a magnetic field (magnetoresistance) can be enormous. This project will investigate the effect of adding magnetic moments to semiconductors. Samples of amorphous Si, Ge, and C doped with magnetic ions such as rare earth elements and Mn will be prepared. Their electronic, magnetic, thermodynamic, and structural properties will be measured over a wide range of temperature, magnetic field, and doping levels. The research will attempt to determine the principles governing the large effect of magnetic moments in amorphous semiconductors. An increased understanding of these effects may point the way to making the very large magnetoresistance of use to the developing spin electronics technology. In addition this research may increase our understanding of why magnetic moments play such a crucial role in other materials of current interest. The project will provide research training and education for two graduate students and an estimated 5-6 undergraduates, including providing them with an exposure to industry and to the national labs through the PI's collaborations. Thus, they will be well prepared for future careers in academia, or industrial or government laboratories.