SUPERCONDUCTING AND MAGNETIC PROPERTIES OF ERBIUM RHODIUM BORIDE
Abstract
Interactions between magnetism and superconductivity have been a topic of considerable interest for some years. The recent discovery of the (RE)Rh(,4)B(,4) and (RE)Mo(,6)X(,8) compounds, where (RE) is a rare-earth atom and X is either S or Se, has enabled a more detailed examination of this interaction. ErRh(,4)B(,4) is perhaps the most interesting of these materials, with a superconducting transition temperature T(,c1) of 8.7 K, and a second transition to the ferromagnetic state which destroys superconductivity at T(,c2) = 0.7 K. Initial measurements on a single crystal sample revealed a number of atypical superconducting and magnetic properties: strong anisotropy in both magnetic and superconducting properties for different crystallographic orientations, an apparent coexistence of superconducting and magnetic order over a narrow temperature range, and other unusual effects. Magnetizaton measurements were taken with the integrator technique for several crystal orientations at temperatures in the range 0.4 (LESSTHEQ) T (LESSTHEQ) 10 K and fields up to 20 kG. This method and other techniques used are discussed, and a deisgn for a new magnetometer system based on a flux-gate detector is presented. New results for the c axis critical fields, superconducting Ginzburg-Landau parameter (kappa), and an incomplete Meissner effect near T(,c2) are presented. The influence of the crystalline electric field on the superconducting and magnetic properties of the material is examined, and the crystal field parameters determined. The magnetization curves were also analyzed to determine the superconducting and ferromagnetic condensation energies, and other properties. Finally, three brief appendices report results of research in other areas: a resistivity anomaly in LiAl, field dependence of the cyclotron effective mass in Pd, and superconducting properties of organic superconductors.
Degree
Ph.D.
Subject Area
Condensation
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