Evaluation of Jc anisotropy in Nd123 single crystals

Abstract

Magneto-optical (MO) measurements were performed for the ac-plane of Nd123 single crystals to evaluate their Jc anisotropy (Jca/Jcc) as functions of temperature, carrier doping level and Nd/Ba composition. Nd123 single crystals with various Nd/Ba compositions were grown by self-flux method. The MO images taken for the ac-plane of Nd123 single crystals were transformed into the magnetic field distribution and Jc anisotropy was evaluated. Jc anisotropy was strongly influenced by carrier concentration, while it was almost unchanged by Nd/Ba composition. Jc anisotropy systematically decreased with an increase of the carrier concentration independent of the Nd/Ba composition. In addition, the notable temperature dependence was not observed in Jc anisotropy between 15 and 50 K. Absolute values of J cc abruptly increase by approaching carrier optimally-doped state due to a decrease in the Jc anisotropy and enhancement of Jca. © 2008 IOP Publishing Ltd.