The thermal and electrical resistance of tin in the intermediate state

Abstract

The thermal and electrical conductivity of tin in its intermediate state has been measured over the temperature range 1·5 to 3·7 °K. The specimens were in the form of cylindrical single crystals with resistance ratios of from 300 to 50 000. Unlike earlier work, particular attention was directed to setting up a domain configuration of known form. It has been found that, provided the transverse magnetic field employed in establishing the intermediate state is suitably rotated as its strength is slowly increased, and provided a small electric current (of some few tenths per cent of the critical) simultaneously flows along the specimen, the thermal resistance is reproducible and stable with time. In addition, a unique variation of electrical resistance with field, which is linear up to the highest temperature examined, of 3·0 °K, is always obtained under these conditions. It is argued that the intermediate state established by this means consists of a stack of cylindrical superconducting and normal laminae. There is strong evidence to suggest that no domains are eliminated in an increasing field until the critical value is reached; when they suddenly disappear and the therm al resistance falls discontinuously to its normal state value. No corresponding discontinuities are observed when the field is reduced to half the critical temperature. Qualitative explanations are offered for these phenomena. The measured temperature variation of the thermal resistivity in the intermediate state is in satisfactory agreement with the theory of Andreev. Magnetothermal resistive effects have also been studied.