Local and Non-local Magnetic Moments in Semiconductors

这一个人研究人员奖将为一个项目提供支持，该项目将调查向半导体添加磁矩的影响。将制备掺杂稀土元素和锰等磁性离子的非晶态Si、Ge和C，并测量它们的电子、磁、热力学和结构性质。声子刚度和半导体带隙对这些性质的影响将被确定。这些附加的局域力矩与电子局域化时金属-绝缘体转变时形成的自发力矩之间的相互作用将被研究。这项研究将为三维金属-绝缘体转变的微观模型提供唯象的支持，并理解在半导体中引入局域磁矩对输运和磁性的影响。该项目将为两名研究生和估计5-6名本科生提供研究培训和教育，包括通过PI与加州大学圣迭戈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--的联系接触工业。磁矩在许多材料(例如，高T_c超导体和巨大的磁阻锰氧化物)中起着关键作用。众所周知，向半导体添加磁矩会产生非常大的影响，但人们对这些影响还没有很好的了解。具体地说，当这种材料置于磁场(磁阻)中时，电阻的变化可能是巨大的。这个项目将研究给半导体增加磁矩的效果。将制备掺有稀土元素和锰等磁性离子的非晶态硅、锗和碳样品。它们的电、磁、热力学和结构特性将在广泛的温度、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态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使极大的磁阻应用于发展中的自旋电子技术指明方向。此外，这项研究可能会增加我们对为什么磁矩在其他当前感兴趣的材料中发挥如此关键作用的理解。该项目将为两名研究生和大约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.