Acquisition of a Measurement System for Research and Education in Magnetic Heterostructures

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This is an award from the Instrumentation for Materials Research program in DMR to the University of Minnesota-Twin Cities. The award supports the acquisition of a measurement system for research and education in magnetic heterostructures. The instrument will support research in four areas of physics and materials science: a) new materials for spin transport in magnetic/semiconductor structures, b) novel magnetic oxide materials and heterostructures, c) exchange bias in ferromagnet/antiferromagnet multilayers and d) two-dimensional conduction in organic crystals. The instrument, which incorporates DC and AC magnetometry and transport over a temperature range of 0.4 to 300 K and in magnetic fields up to 9 T, will be used by students involved in both growth and measurements. In particular, new materials for spin transport, including ferromagnetic semiconductors and half-metallic ferromagnets, will be developed. A variety of new magnetic oxide materials, including cobaltates such as La1-x-SrxCoO3, will be explored, and current work on oxides used as spin injectors will be continued. Microscopic mechanisms for controlling coercivity in multilayers using exchange-induced anisotropy and exchange spring magnetism will be investigated. Finally, low-dimensional transport in organic crystals, with emphasis on superconductivity, will be studied. %%%This award from the Instrumentation for Materials Research program in DMR to the University of Minnesota-Twin Cities supports the acquisition of a measurement system for research and education in magnetic heterostructures at the University of Minnesota. Magnetic heterostructures are "sandwiches" formed by growing thin layers of a magnetic material, such as iron, in combination with other metals, insulators, or even semiconductors. Depending on the particular application in mind, the magnetic material can be either the "meat" or the "bread" in the sandwich. These types of heterostructures are already in use in the latest generation of hard disk drives, and some of the research the new instrument will be dedicated to understanding the microscopic mechanism that is ultimately responsible for the way in which these new drives work. Furthermore, entirely new types of structures, based on magnetic oxides, will be investigated. A new generation of structures, combining the functionality of magnets with those of semiconductors used in transistors, will also be explored. The instrument will be used by graduate students and undergraduates in order to enhance their training in the rapidly evolving field of materials physics.