SPINCATS, an investigation of Spin Caloric Transport in magnetic Semiconductors

就像热电是研究热直接转化为电一样，这里将要研究的自旋热输运（SPINCATS）的新领域是热直接转化为磁，更具体地说，是磁极化。实验将通过探索其在不同类型材料中的特性来了解这种效应是如何发生的。将要解决的特别重要的问题是：(1)这种效应是否可以逆转（即是否存在与磁极化相关的热泵活动）？(2)这种效果是否伴随着余热的额外耗散？自旋-塞贝克效应是由温度梯度引起的自旋极化现象，最近在铁磁性金属、半导体和绝缘体中被发现。这是一种新的热输运现象，是第一个涉及自旋而不是电荷的混合效应。虽然这种影响是真实存在的，但目前还不清楚。该项目将导致对磁极化输运的经典和不可逆热力学性质的基本理解。将研究三种材料类别，MnAs/GaMnAs， EuO和GdGaN。自旋-塞贝克测量作为位置，温度，热梯度和纵向电导率的函数将进行。这些问题将对使用自旋极化作为计算机逻辑（自旋电子学）的基础产生直接的技术影响，这将产生广泛的技术影响。事实上，计算机逻辑电路进一步小型化的主要限制之一是它们会发热，而废热管理在小尺寸上变得势不可挡。虽然自旋极化确实可以成为逻辑电路的基础，但关键是要知道它们会产生多少废热，如果有的话。其他技术应用可能是废热回收或自旋热机。和冰箱。对本科生和研究生在基础和不可逆热力学、化合物半导体异质结构的分子束外延生长、光刻加工、电子、磁性和热电/热磁性表征等领域的培训和研究经历产生了更广泛的影响。学生将被招募到一个跨越机械工程，材料科学和物理的跨学科研究环境中。

Proposal # 1133589PI: Roberto C. Myers, Co-PI Joseph P. HeremansLike thermoelectricity is the study of the direct conversion of heat into electricity, the new field of spin caloric transport (SPINCATS) that will be studied here is the direct conversion of heat into magnetism, more specifically into a magnetic polarization. Experiments will be carried out to understand how this effect occurs by exploring its properties in various types of materials. Particularly important questions that will be addressed are: (1) Can this effect be reversed (i.e. is there a heat pumping activity associated with magnetic polarization)? (2) Is the effect is accompanied by an additional dissipation of waste heat? The spin-Seebeck effect is a spin-polarization induced by a temperature gradient, and was recently discovered in ferromagnetic metals, semiconductors, and insulators. This is a new thermal transport phenomenon, the first mixed effect that involves spins rather than charge. While the effect is real, it is not understood. The project will lead to the fundamental understanding of the classical and irreversible thermodynamic properties of the transport of magnetic polarization. Three material classes will be studied, MnAs/GaMnAs, EuO and GdGaN. Spin-Seebeck measurements as a function of position, temperature, thermal gradient, and longitudinal conductivity will be carried out.The broad technological impacts will come from the fact that these questions have a direct technological impact on the use of spin polarization as the basis for computer logic (spintronics). Indeed, one of the main limitations on the further miniaturization of computer logic circuits is the fact that they heat up, and waste heat management becomes overwhelming at small dimensions. While spin-polarization indeed can be the basis of logic circuits, it is crucial to know how much waste heat they will produce, if any. Other technological applications may be in the recovery of waste heat or in spin-caloric heat ?engines? and refrigerators. Further broad impact arises from the training and research experience for undergraduates and graduate students in the field of fundamental and irreversible thermodynamics, molecular beam epitaxy growth of compound semiconductor heterostructures, lithographic processing, electronic, magnetic, and thermoelectric / thermomagnetic characterization. Students will be recruited into a strongly interdisciplinary research environment spanning Mechanical Engineering, Materials Science, and Physics.