Magnetization of superconducting Hg3−δAsF6

Abstract

The magnetization of the bulk superconducting transition of Hg3−δAsF6 was measured in the temperature range from 0.1 to 1 K and in magnetic fields from 0 to 15 G. The magnetic field was either parallel (H∥c) or perpendicular (H⊥c) to the c axis and was applied in either the field-cooled or the zero-field-cooled mode. The zero-temperature isotropic critical field, after correction for the demagnetization factor, was 16 G and the zero-field transition temperature was 0.42 K. The calculated demagnetization factors can explain the directly measured anisotropic critical fields as well as results obtained from the magnetization versus applied magnetic field curves at constant temperature. These included the ratios of the slopes for the two orientations at low fields, the point of initial flux penetration into the sample, and the average demagnetization factor obtained from the peak of the magnetization curve for H∥c. The observed widths of the superconducting transitions were narrow, with values in the range 100±25 mK. The transitions were 25 mK broader and the hysteresis in an equivalent magnetic field was larger with H⊥c than with H∥c. These secondary effects for H⊥c could not be explained by the anisotropic demagnetization factor and were ascribed to the presence of more extruded mercury detected in the magnetization at 4.15 K. The temperature-dependent magnetization between the bulk Hg3−δAsF6 superconducting transition and the free-mercury transition was explained by the proximity effect between superconducting free mercury and Hg3−δAsF6 metal.

Source-reported materials — not catalogue approval

Similar papers