Hall effect of a linear-chain metal: NbSe3

We present measurements of the low-field Hall constant R_H as a function of field and temperature in the linear-chain metal NbSe₃, The data range from 2 K to 200 K in temperature and up to 15 kG in field. At the two phase transitions T₁ (142 K) and T₂ (58 K) R_H shows an abrupt increase in magnitude but no change in sign. Below 30 K R_H becomes strongly field dependent. The zero-field-limit R_H changes from n-type to p-type at 15 K. It is argued that the results are consistent with a two-band model in which the difference in population p - n is equal to 3 × 10¹⁸ cm^-3 below T₂. The hall data are also consistent with a model in which both a loss of carriers and a drastic change in the conductivity anisotropy occur at T₁ and T₂ and lend support to the charge-density-wave hypothesis which has been used to characterize the two transitions.