Accuracy of 45/spl deg/ torque method for obtaining anisotropy constant of 2D random films

Computer simulation was used to examine the accuracy of anisotropy energy constant, K/sub 2/ of thin film media obtained from the 45/spl deg/ torque method. The easy axes of the media were distributed randomly in plane. The obtained K/sub u/ value depends on range of the applied field. For 2D random media with H/sub K/=1-40 kOe, M/sub s/=100-600 emu/cm/sup 3/, A=0-1/spl times/10/sup -6/ erg/cm, separation between adjacent grains=0-a nm, the difference between obtained K/sub u/ value and exact K/sub u/ was at most 20%, if the range of applied field was larger than 10-20 kOe. Here, the standard values of the physical parameters were H/sub K/=10 kOe, M/sub s/=460 emu/cma, A=0, separation between adjacent grains=0, and each parameter was varied successively.