Magnetic Materials Topics at Texas Materials Institute
A number of faculty in the Texas Materials Institute are investigating magnetic phenomena in a broad range of magnetic materials and magnetic structures. The research activity includes efforts to gain fundamental understanding of technologically-important phenomena in thin films and multilayers, technique development programs in which the goal is to devise new experimental tools for probing and characterizing magnetic behavior, and the synthesis of new magnetic materials and structures based on them, including multilayer stacks, giant magnetoresistance (GMR) and colossal magnetoresistance (CMR) materials, and micro/nanostructures based on these materials.
Thin films and multilayers
Magnetic thin films including multilayer stacks are being used in a broad range of sensor and information storage applications including GMR-based read/write heads and random access memories, and in spin-polarized electron injection devices. Fundamental research on technologically-important phenomena including anisotropy, coercivity, interlayer coupling, domain dynamics, Barkhausen noise and spin-dependent transport is being conducted by faculty within the Texas Materials Institute. A broad range of synthesis capabilities (sputtering, molecular beam epitaxy), magnetic characterization capabilities (Kerr effect, SQUID magnetometry, polarized electron spectroscopy and MFM) and structural evaluation capabilities (LEED, RHEED, STM, AFM, SEM, x-ray diffraction) are available to support the research effort. Instrumentation offering unique capabilities including synchrotron radiation beamlines, low temperature MFM and polarized electron spectrometers are also available.
Novel magnetic materials
Ultrathin magnetic metal films and new compounds based on perovskite structure transition metal oxides exhibit important transport and magnetotransport effects including GMR and CMR behavior. CMR materials (manganites) are being grown by e-beam evaporation and studied using a variety of magnetic sensitive (SQUID, MFM) and transport techniques.
Magnetic microstructures and nanostructures
Mesosopic effects occur when physical dimensions of systems approach chacteristic lengths associated with physical phenomena such as mean free paths, domain widths, and various correlation lengths. Microstructures and nanostructures of magnetic materials fabricated by STM chemical vapor deposition, and contact mask lithography techniques are being used to explore magnetotransport in quantum wires, and domain dynamics in micron scale structures. Excellent theoretical support is available in this subfield of magnetic materials research, specifically mesoscopic phenomena and thin film/surface electronic/magnetic properties.
New probes for characterizing magnetic behavior in thin film structures and nanostructures are being developed by several faculty in the Texas Materials Institute. These techniques include the NMR force microscope, improved MFM instruments based on nanofabricated magnetic tips, Kerr effect microscopes for imaging magnetic domain structure, and a high-speed Kerr effect microscope/polarimeter to study domain wall dynamics and Barkhausen phenomena in ultrathin film structures.
First principles electronic structure calculations of esoteric magnetic properties such as surface ferromagnetism and bulk spiral spin density wave ground states are being performed.
The magnetic materials and the magnetic structures, including multilayer stacks, microstructured and nanostructured materials that are being studied in the TMI, have broad applications in magnetic sensor technology (GMR read-write head, magneto-optic storage) and in device structures (MRAM, spin-injection transistors) that are being developed for microelectronics and communication technology.