MAGNETIZATION DEPENDENCE AND TEMPERATURE-DEPENDENCE OF THE MAGNETIC-ANISOTROPY IN IRON WHISKERS NEAR TC

The magnetic response of an iron whisker grown with its long axis parallel to the [111] direction has been measured up to and through the Curie temperature. The anisotropy constant is found from the response in the range of fields between that necessary to bring the magnetization in the central cross section of the whisker to Ms/sqrt(3) and that to reach Ms. We extract a field proportional to K1/Ms and analyze its dependence on Ms and on temperature. The results indicate that K 1/Ms∼Msn with n=3.11±.05 for the temperature range 0.0005< (Tc-T)/Tc<0.002 with n increasing at lower temperatures. The sensitivity of the method permits the extraction of K1 values over five orders of magnitude.