Regensburg 2010 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 27: CE: Poster Session
TT 27.33: Poster
Wednesday, March 24, 2010, 14:00–18:00, Poster D1
Pressure-induced phase transition in ZnCr2Se4 spinel — •Kaneez Rabia1, Leonetta Baldassarre1, Vladimir Tsurkan2,3, and Christine Kuntscher1 — 1Experimentalphysik II, Universität Augsburg, Germany — 2Experimentalphysik V, Universität Augsburg, Germany — 3Insitute of Applied Physics, Academy of Sciences of Moldova, Chisinau, Republic of Moldova
Among the various transition metal chalcogenide spinels, the chromium spinels with the formula ACr2X4, with A=Zn,Cd or Hg, and X=O,S or Se, were most extensively investigated because of their unusual optical, electrical, and magnetic properties. The Cr3+ ions with the electron configuration 3d3 occupy the B sites with an octahedral environment. Under the action of the octahedral crystal field the Cr 3d levels split into a lower t2g triplet, each orbital being singly occupied, and an excited eg doublet; the resulting bulk material is a Mott insulator with S=3/2. These compounds show a wide variety of magnetic properties ranging from those of a strongly frustrated antiferromagnet to a Heisenberg ferromagnet.
In the present study we studied the optical response of ZnCr2Se4 in refection mode as a function or pressure. Our results suggest the occurrence of a sluggish structural phase transition and the tendency of charge delocalization starting from 12 GPa. We will also discuss the pressure dependence of the high-energy electronic excitations, which are assigned to onsite crystalfield transitions.