Magnetic-field-induced resistance upturn in Al2O3/SrTiO3 heterostructures

Abstract

Some topological semimetals with extremely large magnetoresistance usually exhibits an interesting physical phenomenon: resistance shows an upturn as temperature decreases when the external magnetic field is over certain value. Here, we study the magnetotransport properties of wide-bandgap oxide-based Al₂O₃/SrTiO₃ heterostructures prepared by magnetron sputtering. Two samples are of high quality, with large residual resistivity ratio (larger than 1500). A well-defined magnetic-field-induced resistance upturn is clearly observed at low temperature for each sample, indicating that it is not a unique property of topological semimetals. The observed phenomenon cannot be attributed to the electron-hole compensation although the multiple carriers transport occurs in our samples. The metal-insulator transition cannot be used to explain our observation, either. We attribute it to the weak antilocalization effect while the field-induced resistance upturn is further enhanced by the presence of large linear magnetoresistance.