MAGNETOTRANSPORT AND SPECIFIC-HEAT PROPERTIES IN THE CHARGE-DENSITY-WAVE STATE OF THE QUASI-2-DIMENSIONAL BRONZES (PO2)4(WO3)2M (M = 4,6,7)

Hall effect and specific heat have been measured on single crystals of P4W8O32, P4W12O44 and P4W14O50. The Hall constant is small in the hig h temperature normal state and \R(H)\ increases at the Peierls transit ions, corroborating the existence of charge density wave gap openings. Specific heat data show that the Debye temperature is in the range 24 0 K-280 K. Anomalously large gamma coefficients of the linear contribu tion to the specific heat are found. In the case of P4W14O50, an anoma ly found around 45 K provides values of the enthalpy and entropy chang es at the low temperature transition.