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≊40 °C) is observed. The concomitant large pyromagnetic (d ln 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.