Magnetoimpedance of Ultrathin Films and Thin-Film Interfaces

University Of Florida, Gainesville FL

Investigators

Abstract

Technical Abstract: In this individual investigator grant we utilize complex impedance measurement techniques to characterize the effect of magnetic fields on electrical transport in thin-film structures. The particular topics under study are: (1) the collapse of itinerant ferromagnetism in the extreme disorder limit as monitored by in situ anomalous Hall measurements, (2) the sensitivity of the interfacial magnetocapacitance contributions to the surface proximity of ultrathin buried Fe layers in host Pd electrodes, (3) a heretofore unrecognized 'giant' magnetocapacitance contribution in lightly doped MOS and Schottky barrier structures fabricated using both standard and magnetic semiconductors, and (4) the acquisition and analysis of the frequency response of the complex dielectric constant in anisotropic or layered correlated electron systems where insulating phases compete with metallic phases that are either magnetic (e.g., manganites) or superconducting (underdoped high Tc). Results are expected to give considerable insight into understanding magnetic properties at the interfaces of complex materials that show promise for use in magnetoelectronics and nanotechnology. Students working on this project will disseminate their results within the scientific community and learn thin-film growth and characterization skills that are highly marketable in industrial, government or academic environments. Non-Technical Abstract: This proposed work will focus on understanding the physics of magnetism at planar interfaces using electrical measurement techniques that can simultaneous sense the effect of magnetic field on the mobility of electrons and on the number of electrons present. For our purposes an interface-dominated magnetic system can be an ultrathin magnetic film, a planar interface between two dissimilar materials, a tunnel junction with magnetic electrodes, or a bulk system in which there are coexisting and competing phases, at least one of which is magnetic. Answers to scientific questions addressed in this proposal, such as "How does magnetism survive at interfaces?", "How small can a system be made before ferromagnetic ordering disappears?" and "How efficiently can spin-oriented electrons be transferred across an interface?", are expected to help provide an understanding of the potential of magnetoelectronics in future technology. Students working on this project will disseminate their results within the scientific community and learn thin-film growth and characterization skills that are highly marketable in industrial, government or academic environments.