Colossal Magnetoresistive p-n Junctions of Te-Doped LaMnO₃/Nb-doped SrTiO₃

We have fabricated colossal magnetoresistive (CMR) p-n junctions made of Te-doped LaMnO₃ and Nb-doped SrTiO₃ with laser molecular beam epitaxy. The I-V characteristics of the La_0.9Te_0.1MnO₃/SrNb_0.01Ti_0.99O₃ p-n junctions as a function of applied magnetic field (0-5 T) were experimentally studied in the temperature range 77-300 K. The results indicate that the p-n junction exhibited the CMR behaviour. The magnetoresistance (MR) is positive at 220 K and 300 K, while it displays a negative MR at 77 K. For a positive bias, the MR ratios (ΔR/R₀, ΔR = R_H-R₀) are 7.5% at 0.1 T and 18% at 5 T for 300 K, 5% at 0.1 T and 33% at 5 T for 220 K, -14% at 0.1 T and -71% at 5 T for 77 K. For a negative bias, the MR ratios are 6.3% at 0.1 T and 10.8% at 3 T for 300 K, 5.1% at 0.T and 15% at 3 T for 220 K, -19% at 0.1 T and -72% at 5 T for 77 K. The CMR behaviour of the p-n junction is different from those of the LaMnO₃ compound family.