TUNNEL-DIODE OSCILLATOR APPLICATION TO HIGH-SENSITIVITY DE-HAAS-VAN-ALPHEN AND SUPERCONDUCTING CRITICAL-FIELD STUDIES OF ANISOTROPIC ORGANIC CONDUCTORS

We report the first application of a tunnel diode circuit to investiga te the de Haas-van Alphen effect and superconducting critical field va lues in small single crystal organic conductors. The materials of inte rest are in the family of charge transfer salts (BEDT-TTF)2X, where X is one of a number of anion structures. Small (less-than-or-equal-to 1 mm3) oriented single crystal samples were placed inside the inductanc e coil of the LC tank circuit of the oscillator, and measurements were carried out at low temperatures and in high magnetic fields. We obser ve a marked improvement over previous magnetic methods for the determi nation of both de Haas-val Alphen signals and for critical field studi es. The method is applicable where such information is required for ve ry small samples.