Momentum Dependent Spectral Changes Induced by the Charge Density Wave in2HTaSe2and the Implication on the CDW Mechanism

Abstract
We report a high energy and high angular resolution angle resolved photoemission study of 2HTaSe2 at temperatures both above and below the charge-density-wave (CDW) transition. In the normal state, an extended saddle band very close to the Fermi energy was observed. The CDW-induced energy gap is near zero on a well defined Fermi surface and large in the extended saddle band region. The implication of these results on the CDW mechanism is discussed.