Harcourt Brown

Magneto-optical indicator film study of the magnetization of a symmetric spin valve

A magneto-optical indicator film (MOIF) technique is used for direct experimental study of the magnetization reversal process in a symmetric NiO/Co/Cu/NiFe/Cu/Co/NiO spin valve. It is shown for the first time that the reversal of the free center layer proceeds by nonuniform magnetization rotation. The observed switching mechanism is presumed to be associated with the influence of the nonuniform magnetostatic field that follows from surface roughness and the polycrystalline structure of the magnetic layers.

Spin Reorientation Transitions And Domain Structure In Magnetic Multilayers

Spin reorientation phase transitions and the evolution of the magnetic phases states arising during magnetization reversal of antiferromagnetic CoNiCu/Cu superlattice are studied using magneto-optical indicator film technique, accompanied by vector hysteresis loop measurements. The spin-flop and nonsymmetric angle phases have been found and analyzed. It is shown that they arise due to the nucleation and growth of domains.

Magnetism and incommensurate waves in Zr3(Rh1−xPdx)4

Unique properties of the Zr3(Rh(1−x)Pdx)4 alloy system are reported here. Contrary to most metallically bonded systems which are not quick to change magnetic behavior with alloy concentration, this system does. Pure Zr3Rh4 and pure Zr3Pd4 are each nonmagnetic, while in the limited range 0.02<x<0.08, there is a substantial increase in paramagnetism, attended by a similarly varying incommensurate density wave. At x=0.04 the system exhibits ferromagnetism and displays some superconductivity at x=0.06. The crystal structure involves disclination lines of Rh atoms, or channels, which are equivalent to those of the superconducting A15 structures and bear resemblances to those of the hard magnets.

Origins of coercivity increase in annealed symmetric spin valves

Measurements of the effects of annealing on symmetric Co/Cu spin valves and similar structures show increased coercivity, increased ferromagnetic resonance linewidth and reduced moment. Low angle X-ray reflectivity measurements indicate that there is some oxidation throughout the thickness of the metal films during annealing. The layer structure, as determined from low-angle X-ray reflectivity and magnetoresistance values is only weakly affected by annealing at 250 C. We conclude from these results that the Cu/Co interfaces are not strongly affected, and we suspect that the thermally induced changes in these include partial oxidation which occurs mainly in the grain boundaries, which lie perpendicular to the film plane.

Letters to a President: Higher Education in the British Isles

IV LONDON, 6 December 1960 DEAR BARNABY, We are a little stale after two and a half months, even though there has been much variety in them. We have seen eight universities, talked with unnumbered faculty, four vice-chancellors, a fair number of students, and several librarians. I have a file of clippings from the Times, Observer, Guardian, and other papers, and a collection of books, offprints, and pamphlets. This part of the academic sabbatical is now ending, and we shall, after the New Year, be pursuing the scholarly ends for which I have mostly come abroad. Southampton was excellent, and we have pressing invitations to come back, to talk to students, and perhaps to give a lecture or take a class. At dinner on our last night there, I met two historians, the professors of English Literature, Classics, German, and French, and the Bursar; with J. and myself we had a table where conversation was possible. I was asked to give my impressions of British Universities, which need not be repeated here; I was interested to see the variety of reactions to suggestions about the danger of too much stuffing as opposed to the stimulating of inquiry and research. The thought that expansion might be handled by the creation of new departments, Anthropology, History of Art, History of Science, Russian Studies, and so on, was strange also, and not exactly liked. J. is anxious to see the autonomy of departments broken down, more interchange between disciplines, the development of wider studies as opposed to the traditional pattern of Honours courses. Quite recently, Southampton has abandoned the general course; one comment we picked up was that it had not been much liked by students because the work was as hard as in the Honours fields, and asked for a scattering of effort, while in Honours one could concentrate and get better marks more easily. But I do not think the teaching staff quite appreciate the significance of the comment. On the way back to London we had about five hours in Reading, small but dynamic, a place to return to when I can. This University