TEXTURING FROM LIQUID TO SOLID STATE BY ALIGNING ANISOTROPIC MAGNETIC NUCLEI IN HIGH FIELDS

摘要

High magnetic fields are used to texture materials still having a small magnetic anisotropy near their melting temperature T_m. The magnetic alignment along an easy-magnetization axis is maximum after a full melting and an overheating rate smaller than a critical value t_c = (T_c-T_m)/T_m followed by cooling and solidification in a magnetic field. Cooling from T > T_c produces some surfusion indicating the disappearance of nuclei for the crystal growth. The critical radius R_c of nuclei can be magnetically determined and related to the electrostatic double-layer of conduction electrons at the solid-liquid interface that is stabilizing their free energy above T_m. The effective influence of this electrostatic interaction could be evaluated by studying the critical temperature T_c and the contact potential Δφ between a solid and its melt.