Broken Hexagonal Symmetry in the Incommensurate Charge-Density Wave Structure of2H-TaSe2

Abstract
High-resolution x-ray scattering studies show a new charge-density wave (CDW) structure on warming through the commensurate-incommensurate transition in 2H-TaSe2 at 93 K. In contrast to the fully incommensurate CDW structure seen on cooling, hexagonal symmetry is broken in the new phase and the triple-q CDW has one commensurate and two incommensurate wave vectors. At 112 K (warming) the CDW transforms to the fully incommensurate structure.