Single-crystal NMR for the layered semiconductorTlGaSe2

Abstract

We report on a 69Ga and 205Tl NMR study of single-crystal thallium gallium selenide. Our findings show that transformationfrom the high temperature paraelectric phase to the low temperature ferroelectric phaseoccurs via an incommensurate phase that exists in the temperature range fromTc = 107.5 toTi = 118 K. On approachingphase transition at Ti from above, the crystal exhibits soft mode behavior, which is somewhatdifferent for thallium and gallium substructures. Redistribution of69Ga line intensities with temperature in the ferroelectric phase indicates a variation of thedomain structure of this phase.