Magnetic oscillations in the organic conductor (TMTSF)/sub 2/NO/sub 3/ - FERMI surface and physical properties

Abstract

Summary form only given. We studied the Fermi surface of the organic conductor (TMTSF)/sub 2/NO/sub 3/ through the measurements of magnetic quantum oscillations. Two different families of oscillations are observed. Well defined Shuvnikov-de Haas(SdH) oscillations with frequency of ca. 60T can be observed below 8K and above 6T at the ambient pressure. The higher frequency oscillations reported elsewhere is not visible be low 12T. The angular magnetoresistance does not show any structure neither at Yamaji's magic angles nor at Lebed's resonance condition. Only the SdH oscillations for the field scaled by Cos /spl theta/ are added and easily separated. Under a pressure of 10kbar, different oscillations with frequency of ca. 200T is observed above 10T at 450mK. Even though it is the same frequency as so called rapid oscillations observed in other Bechgaard salts, angular dependence of oscillation frequency does not follow the simple cosine law contrary to that of (TMTSF)/sub 2/CIO/sub 4/. The amplitude of oscillations depend very oddly with sample orientation, too. Both suggest that the electron structure at low temperature is strongly modified upon application of pressure which may explain the absence of superconductivity and the field-induced spin-density waves. The angular magnetoresistance shows actually three maxima at angles which are not determined from the known theories.