Transport and thermal behavior of the charge density wave phase transition in CuTe

Abstract

Copper monotelluride CuTe is of current interest due to the discovery of the quasi-one dimensional charge density wave (CDW) behavior below the transition temperature ${T}_{\mathrm{CDW}}\ensuremath{\simeq}335\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. To explore the transport and thermodynamic properties and provide experimental insights into the underlying origins of the CDW, we have carried out a combined study by means of the electrical resistivity, Seebeck coefficient, thermal conductivity, as well as specific heat measurements on single crystalline CuTe. The CDW phase transition has been characterized by marked features near ${T}_{\mathrm{CDW}}$ from all measured physical quantities. In particular, the observed Seebeck coefficient and electronic thermal conductivity exhibit a pronounced reduction as cooling the temperature across ${T}_{\mathrm{CDW}}$, indicative of the partially gapped Fermi surfaces associated with the CDW formation. From the examination of the excess specific heat in the vicinity of ${T}_{\mathrm{CDW}}$, we obtained evidence for the strong-coupling character of the CDW, suggesting that the electron-phonon coupling plays an important role for the CDW instability in CuTe.