Professor Stephen Blundell

Abstract:

We have used polarized neutron reflection to determine the layer-dependent spin orientations in an antiferromagnetically coupled 100 Angstrom Cr/50 Angstrom Fe/15 Angstrom Cr/50 Angstrom Fe/Si sandwich structure prepared by sputtering. At low field, the net Fe layer magnetic moments align in an asymmetric canted orientation with a near zero total magnetic moment for the sample. At high fields, a canted state, nearly symmetric with respect to the applied field direction is observed and the magnetization in each layer does not reach the bulk saturation value until the layers are ferromagnetically aligned. The behavior is discussed in the context of current theories of exchange coupling. (C) 1996 American Institute of Physics.

Abstract:

Recent experimental studies of the angle-dependent magnetoresistance in various organic metals have been remarkably successful in elucidating the nature of the low-temperature ground state and providing information about the Fermi surface shape which is hard or impossible to obtain using other techniques. We review various theoretical approaches to describe angle-dependent magnetoresistance and a number of important experimental results which have been obtained. ©Les Éditions de Physique 1996.

Abstract:

We report the results of muon-spin-rotation/relaxation (μ+SR) experiments on two recently discovered nitronyl nitroxides, 1- and 2-naphthyl nitronyl nitroxide (1-NAPNN and 2-NAPNN). These two compounds are chemical isomers but, because of their slightly different molecular shapes, they have quite different crystal packing. A clear magnetic transition in the zero-field muon-spin relaxation is observed in 1-NAPNN below 100 mK while no such transition is seen in 2-NAPNN. These results support the postulate that the crystal structure strongly influences the nature of the magnetic ground states in these materials.