Magnetic two-dimensional electron gases at the oxide interfaces are always one of the key issues in spintronics, giving rise to intriguing magnetotransport properties. However, reports about magnetic two-dimensional electron gases remain elusive. Here, we obtain the magnetic order of LaAlO/SrTiO systems by introducing magnetic dopants at the La site. The transport properties with a characteristic of metallic behavior at the interfaces are investigated. More significantly, magnetic-doped samples exhibit obvious magnetic hysteresis loops and the mobility is enhanced. Meanwhile, the photoresponsive experiments are realized by irradiating all samples with a 360 nm light. Compared to magnetism, the effects of dopants on photoresponsive and relaxation properties are negligible because the behavior originates from SrTiO substrates. This work paves a way for revealing and better controlling the magnetic properties of oxide heterointerfaces.

The thickness of perovskite absorber layer is a critical parameter to determine a planar structured perovskite solar cell's performance. By modifying the spin coating speed and PbI 2 /N,N-dimethylformamide (DMF) solution concentration, the thickness of perovskite absorber layer was optimized to obtain high-performance solar cells. Using a PbI 2 /DMF solution of 1.3 mol/L, maximum power conversion efficiency (PCE ) of a perovskite solar cell is 15.5% with a perovskite film of 413 nm at 5000 rpm, and PCE of 14.3% was also obtained for a solar cell with a perovskite film of 182 nm thick. It is derived that higher concentration of PbI 2 /DMF will result in better perovskite solar cells. Additionally, these perovskite solar cells are highly uniform. In 14 sets of solar cells, standard deviations of 11 sets of solar cells were less than 0.50% and the smallest standard deviation was 0.25%, which demonstrates the reliability and effectiveness of hybrid physical chemical vapor deposition (HPCVD) method.

Complex oxide heterointerfaces provide a platform to manipulate spin−orbit coupling under the broken inversion symmetry. Moreover, their weak antilocalization (WAL) effect displays quantum coherent behavior due to the strong spin−orbit coupling. Herein, we break through the limitation of lattice mismatch at ReAlO 3 /STO (Re = La, Pr, Nd, Sm, and Gd) heterointerfaces and obtain their twodimensional electric gas (2DEG) by spin coating. The effect of different Re elements in the resulting quantum corrections on the conductivity is investigated. It is observed that the conductivity of heterointerfaces is reduced with larger atomic numbers due to the ionization potential of Re elements. Moreover, magnetoresistance (MR) measurements in a perpendicular or a parallel field distinctly uncover strong Rashba spin−orbit coupling (SOC) in ReAO/STO samples besides SAO/STO (Re = Sm) and GAO/STO (Re = Gd), and the effective fields of the SOC (H so ) gradually increase from LAO/STO (Re = La, H so = 0.82 T) to NAO/ STO (Re = Nd, H so = 1.37 T) at 2 K. The competition between SOC scattering and inelastic scattering is revealed through a temperature-dependence study of MR, and the WAL−weak localization transition is at about 6 K. Furthermore, unambiguous results of the Kondo effect, nonlinear Hall, hysteresis loop, and Rashba SOC suggest the coexistence of WAL at the PAO/STO (Re = Pr) heterointerface with exchange coupling between the localized magnetic moment and the itinerant electron. These results pave a unique route for the exploration of spin-polarized 2DEGs at oxide heterointerfaces.

Although the amorphous two-dimensional electron gas (a-2DEG) of oxides provides new opportunities to explore nanoelectronic as well as quantum devices, the intrinsic effect of rare earth (Re = La, Pr, Nd, Sm, Gd, and Tm) elements at ReAlO 3 /SrTiO 3 heterointerfaces is still largely unknown and needs to be addressed systematically. Herein, we first propose that the ionization potential of Re elements is a critical factor for the 2DEG fabricated by chemical spin coating. Furthermore, the photoresponsive properties of heterointerfaces are investigated comprehensively with the ionization potential ranging from 35.79 to 41.69 eV. The results show that the sheet resistances significantly increase with increasing the ionization potential, and a resistance upturn phenomenon is observed at TmAlO 3 /SrTiO 3 heterointerfaces, which can be attributed to the weak localization effect theoretically. The most important observation is the dramatic transition from negative (−178.3%, Re = La) to positive (+89.9%, Re = Gd) photoresponse at ReAlO 3 /SrTiO 3 heterointerfaces under the irradiation of 405 nm light at 50 K. More remarkably, a unique recovery behavior of transient−persistent photoconductivity coexistence at low temperatures is discovered at the TmAlO 3 /SrTiO 3 heterointerface. This work reveals an effective approach to tune the transport and photoresponsive properties by changing Re elements and paves the way for the application of all-oxide devices.

The electric, magnetic, and thermal properties of transition metal oxide films can be modulated by introducing polycrystalline at the macroscopic grain boundaries. Based on these points, in this work, we studied the two-channel anomalous Hall effect (AHE) in polycrystalline ferromagnetic SrRuO3 (SRO) films. The magnetic regions with different crystal directions have different coercivities, resulting in two opposite AHE channels in the polycrystalline SRO layer. However, single-crystal SRO films prepared under the same conditions are found to exhibit only one AHE. The superposition of the two AHE leads to the hump-like behavior of the Hall resistance loop, which is caused by the change of crystalline. This observation provides a new way to explain the hump-like feature of SRO.