Anomalous anisotropic magnetoresistance in single-crystalline Co/SrTiO₃(001) heterostructures

The anisotropic magnetoresistances (AMRs) in single crystalline Co(6 nm)/SrTiO₃(001) heterostructures from 5 K to 300 K with the current direction setting along either Co100 or Co110 are investigated in this work. The anomalous (normal) AMR is observed below (above) 100 K. With the current along Co100 direction, the AMR shows negative longitudinal and positive transverse magnetoresistances at T< 100 K, while the AMR is inverse with the current along Co110. Meanwhile, the amplitude ratio between Co110 and Co100 is observed to be as large as 29 at 100 K. A crystal symmetry-adapted model of AMR demonstrates that interplay between the non-crystalline component and crossed AMR component results in the anomalous AMR. Our results may reveal more intriguing magneto-transport behaviors of film on SrTiO₃ or other perovskite oxides.