THERMAL EFFECT ON THE COERCIVITY OF ULTRATHIN NIFE FILMS

The temperature dependence of the coercivity of ultrathin NiFe films w as measured by SQUID in the temperature range from 5 to 300 K. Tile ch ange in coercivity with temperature was much greater for thinner films than for thicker ones. A domain wall motion model is proposed to expl ain the experimental results. It is concluded that the intrinsic coerc ivity increases rapidly with decreasing the thickness, especially in t he range of several nm, and that the low coercivity observed for very thin films at room temperature is ascribed primarily to the thermal ef fect.