Giant fluctuation magnetoresistance in MnAs thin films

We present the similarity in magnetic and transport properties of MnAs and perovskite La1-xCaxMnO3 thin films which exhibit a colossal magnetoresistance. Submicron thickness magnetic MnAs films exhibiting a continuous magnetic phase transition have been molecular beam epitaxy grown on sapphire substrates. A giant magnetoresistance (of order of 10% at H = 10 kOe) arising from critical spin fluctuations in the vicinity of phase transition (T approximate to 40 degrees C) is observed. The concomitant large pyromagnetic (d In M/dT = -0.5 K-1) and pyroresistive (d ln R/dT = 0.046 K-1) effects along with a high magnetoresistance make MnAs films promising for applications. (C) 1996 American Institute of Physics.