Charge density wave formation, superconductivity and Fermi surface determination in NbSe₃: a pressure study

Abstract

The resistance of single crystals of NbSe3 under pressure, between 1.2 and 70K has been measured in magnetic fields up to 180 kG. The CDW which appears at ambient pressures at 59K, is totally suppressed for pressures greater than 5.5 kbar. At this pressure NbSe3 is fully superconducting as shown by a total Meissner effect. Fermi surface studies by Shubnikov-de Haas oscillations show that the Fermi surface is strongly affected by the CDW formation. At ambient pressure, when H is parallel to the plane (b, c) one frequency (0.3 MG) is detected, but when the pressure has suppressed the CDW, at least eight frequencies (up to 7 MG) were detected. The experiments are consistent with the model of different types of chains in NbSe3 on which the two CDW form.