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Title:Magneto-transport properties of giant magnetoresistive systems
Author(s):Shi, Jing
Doctoral Committee Chair(s):Salamon, Myron B.
Department / Program:Physics
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Physics, Condensed Matter
Abstract:To understand the cause of the giant magnetoresistance effect, we have systematically investigated magnetothermopower, magneto-thermal conductivity and magnetoresistivity in both ferromagnetic/non-magnetic multilayers and granular solids which exhibit the giant magnetoresistance effect.
A large magnetic field-dependent diffusion thermopower, S(H, T), was found to accompany the giant magnetoresistance in these systems. The thermopower is closely correlated with the resistance at all temperatures examined as the magnetic field varies, indicating that the same underlying mechanism is responsible for both the giant magnetothermopower and magnetoresistance effects. We have concluded that the spin-split density-of-states (DOS) of the ferromagnetic d-bands provides the needed asymmetry in both spin conduction channels, and therefore is the fundamental cause of these effects.
The Wiedemann-Franz law was found to be well obeyed by the field dependent electrical and thermal conductivities in granular systems. The Lorentz number is a weak function of temperature. Both facts demonstrate that the scattering causing the GMR effect is primarily elastic in granular solids. However, the Lorentz number is magnetic field-dependent in multilayer systems, indicating that the spin-flip scattering into the spin-split d-bands is important.
Issue Date:1994
Rights Information:Copyright 1994 Shi, Jing
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9512548
OCLC Identifier:(UMI)AAI9512548

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