Gate tunable Rashba spin-orbit coupling at CaZrO3/SrTiO3 heterointerface

High mobility quasi two-dimensional electron gas (2DEG) found at the CaZrO₃/SrTiO₃ nonpolar heterointerface is attractive and provides a platform for the development of functional devices and nanoelectronics. Here we report that the carrier density and mobility at low temperature can be tuned by gate voltage at the CaZrO₃/SrTiO₃ interface. Furthermore, the magnitude of Rashba spin-orbit interaction can be modulated and increases with the gate voltage. Remarkably, the diffusion constant and the spin-orbit relaxation time can be strongly tuned by gate voltage. The diffusion constant increases by a factor of ～ 19.98 and the relaxation time is reduced by a factor of over three orders of magnitude while the gate voltage is swept from -50 V to 100 V. These findings not only lay a foundation for further understanding the underlying mechanism of Rashba spin-orbit coupling, but also have great significance in developing various oxide functional devices.     

钛酸钡介电调控提升纸基摩擦纳米发电机输出性能

摩擦纳米发电机作为一种能够将机械能转换为电能的新型能源转换装置,自发明以来便引起了广泛关注,然而其环保性能由于原料来源多为合成高分子材料而受到制约.采用绿色环保的纤维素材料制备摩擦纳米发电机是解决上述问题的重要方式之一.本研究以竹纤维素和钛酸钡(BaTiO₃)为原料,结合湿法造纸和掺杂改性制备了纤维素/钛酸钡复合纸,并将其作为正极摩擦层构建了纸基摩擦纳米发电机(cellulose/barium titanate-triboelectric nanogenerator,C/BT-TENG).结果表明,BaTiO₃的加入显著提升了复合纸的相对介电常数,C/BT-TENG的输出性能随着BaTiO₃掺杂量增加而提升,在4%掺杂量时,C/BT-TENG的开路电压和短路电流达到最大值118.5 V和13.51μA,相比纯纤维素纸作为正极摩擦层时,分别提升了51.3%和41.2%.通过模型法分析了介电调控提升C/BT-TENG输出性能的机理.此外,C/BT-TENG具有良好的输出性能和工作稳定性,在负载电阻为5 MΩ时,其获得最大输出...     

Sign reversal of anisotropic magnetoresistance and anomalous thickness-dependent resistivity in Sr2CrWO6/SrTiO3 films

High-quality Sr₂CrWO₆ (SCWO) films have been grown on SrTiO₃ (STO) substrate by pulsed laser deposition under low oxygen pressure. With decrease of the film thickness, a drastic conductivity increase is observed. The Hall measurements show that the thicker the film, the lower the carrier density. An extrinsic mechanism of charge doping due to the dominance of oxygen vacancies at SCWO/STO interfaces is proposed. The distribution and gradient of carrier concentration in SCWO films are considered to be related to this phenomenon. Resistivity behavior observed in these films is found to follow the variable range hopping model. It is revealed that with increase of the film thickness, the extent of disorder in the lattice increases, which gives a clear evidence of disorder-induced localization charge carriers in these films. Magnetoresistance measurements show that there is a negative magnetoresistance in SCWO films, which is considered to be caused by the magnetic scattering of magnetic elements Cr³⁺ and W⁵⁺. In addition, a sign reversal of anisotropic magnetoresistance (AMR) in SCWO film is observed for the first time, when the temperature varies across a characteristic value, T_M. Magnetization—temperature measurements demonstrate that this AMR sign reversal is caused by the direction transition of easy axis of magnetization from the in-plane ferromagnetic order at T > T_M to the out-of-plane at T < T_M.