Large Magnetoresistance Anisotropy in Strained Pr 0.67 Sr 0.33 MnO 3 Thin Films

We have studied the anisotropic magnetoresistance (AMR) of strained Pr 0.67 Sr 0.33 MnO 3 thin films by measuring the MR as a function of the angle between the magnetic field direction and the substrate normal (out-of-plane). The results show that the compressive- and tensile-strained ultrathin films (5-15 nm) grown on LaAlO 3 (001) (LAO) and SrTiO 3 (001) (STO) substrates show unusually large out-of-plane AMR, but with opposite signs. In contrast, the almost strainfree films on the NdGaO 3 (110) substrates show much smaller AMR over all the temperature and field ranges studied. Thick films on LAO and STO substrates also show much smaller AMR.