Charge-density-wave transitions in 1T-VSe2

Abstract
An electron diffraction and imaging study of charge-density-wave phases in 1T-VSe2 is presented. Two phase transitions are found. At 110K a 3q-state is formed which at 80K transforms into an irregular pattern of 2q-domains. A Landau theory of these transitions is presented. In order to explain the 3q-2q transition sixth-order terms must be included in the free-energy expansion.