Large positive magnetoresistance in photocarrier-doped potassium tantalites

We report on the high-field magnetotransport of KTaO ₃ single crystals, which are a promising candidate for study in the extreme quantum limit. By photocarrier doping with 360 nm light, we observe a significant positive, non-saturating, and linear magnetoresistance at low temperatures accompanied by a decreasing Hall coefficient. When cooling down to 10 K, the magnetoresistance value of KTaO ₃ (100) reaches ∼ 433% at a magnetic field of 12 T. Such behavior can be attributed to all the electrons occupying only the lowest Landau level in the extreme quantum limit. Light inhomogeneity may also contribute to large linear magnetoresistance. These results provide insights into novel magnetic devices based on complex materials and add a new family of materials with positive magnetoresistance.