NEUTRON-DIFFRACTION STUDIES OF ZINCBLENDE MNTE EPITAXIAL-FILMS AND MNTE ZNTE SUPERLATTICES - THE EFFECT OF STRAIN AND DILUTION ON A STRONGLY FRUSTRATED FCC ANTIFERROMAGNET/

We report neutron-diffraction studies of antiferromagnetism in various forms of epitaxially grown zinc-blende (ZB) MnTe: in semibulk (approx imately 1 mum thick) single-crystal films of pure MnTe, in its magneti cally diluted derivative Zn1-xMnxTe with 0.695 < x < 1, and in strongl y strained very thin (30-300 angstrom) single-crystal MnTe layers in M nTe/ZnTe superlattices. ZB Mn chalcogenides are unique examples of fcc Heisenberg antiferromagnets (AF) with dominant nearest-neighbor inter actions. Such a lattice is one of the basic models of topologically fr ustrated spin systems. Only ZB MnS can be obtained through natural cry stallization (and only in a fine powder form, which seriously limits t he scope of possible studies on this system). The single-crystal forms of MnTe obtained using molecular-beam epitaxy have made it possible t o study the influence of strain on a frustrated fcc antiferromagnet. W e observe that such built-in strain strongly affects the domain struct ure as well as the phase-transition behavior. Furthermore, high-resolu tion x-ray diffraction reveals pronounced magnetostriction effects in the MnTe films. Both neutron as well as x-ray data indicate a rather u nusual effect of a strong temperature shift in the relative population s of two inequivalent AF domain states, and a magnetosctriction mechan ism underlying this phenomenon is proposed. Finally, the data obtained on Zn1-xMnxTe films complement the results of previous magnetic studi es on bulk forms of this material with x less-than-or-equal-to 0.68.