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A physicist who, with W. H. Meiklejohn, reported exchange bias in particles combining a ferromagnetic metal and an antiferromagnetic oxide. The interface introduces a preferred magnetic direction through coupling between the two materials. This showed that the contact between different magnetic orders can change how a material reverses its magnetization, rather than merely adding their separate responses.^[ref]

Heat the bilayer into a window $T_N<T<T_c$, apply an in-plane magnetic field sufficient to align the ferromagnet, and cool through the antiferromagnet's ordering/blocking range while retaining the field. The ferromagnet supplies a preferred interfacial spin direction as the antiferromagnet orders. Sufficient antiferromagnetic anisotropy then pins part of the interfacial spin configuration, producing unidirectional magnetic anisotropy rather than merely uniaxial magnetic anisotropy in the ferromagnet.

Measure a full major hysteresis loop after removing the cooling field, and compare with the isolated ferromagnet, a zero-field-cooled bilayer and the result of reversing the cooling-field direction. Those controls separate a true loop-centre shift from a changed coercive width, minor-loop artefacts or trapped applied field. The effect requires appropriate interfacial exchange and stable pinning; an ideally compensated or freely rotating interface need not produce a large bias. Exchange anisotropy in coupled ferromagnetic/antiferromagnetic material was demonstrated in the classic experiment below.^[ref]

A physicist who coauthored the discovery of exchange bias with C. P. Bean. Their cobalt particles had an oxide shell, placing ferromagnetism in direct contact with antiferromagnetism. The resulting directional effect in magnetic reversal made the interface an active part of the experiment and motivated the study of coupling between unlike magnetic materials.^[ref]