部分填充水平旋转圆柱筒内涂层流动的实验研究

通过改变液体的动力黏度、填充体积分数(液体体积与圆柱筒容积之比)、圆柱筒转速等实验参数,对部分填充了粘性液体的圆柱筒在绕其水平对称轴旋转时,圆柱筒内液体自由表面出现的各种现象进行了实验探究和初步定性解释.并作出了当固定液体黏度时转速与填充体积分数的实验相图和固定填充体积分数时转速与黏度的实验相图.     

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.     

LaAlO3/SrTiO3异质界面磁场调控的反常金属态

自LaAlO₃/SrTiO₃异质界面发现高迁移率的二维电子气以来,其二维超导电性、界面磁性和自旋轨道耦合等诸多物理性质已经被广泛研究.对于二维超导体,零温下超导-反常金属相变的起源仍然是一个悬而未决的问题.传统理论认为在超导-绝缘量子相变中只存在2种基态,即库珀对的超导基态和绝缘基态.然而在研究超导颗粒膜中超导电性的演化与厚度和温度的关系时发现,存在一个中间金属态破坏了超导体和绝缘体之间的直接过渡.这种中间金属态的标志性特征是,在超导转变温度之下存在饱和的剩余电阻,与之对应的基态称作反常金属态.本文主要对在LaAlO₃/SrTiO₃(001)异质界面磁场诱导的超导-反常金属量子相变进行了系统的研究.在没有外加磁场的情况下,电阻-温度(R-T)曲线和电流-电压(I-V)特性曲线表明样品在超导转变温度之下处于超导态.外加磁场会导致样品在低温下出现饱和电阻、正的巨磁阻和低电流范围内的线性I-V曲线.另外,霍尔电阻在一定的磁场之下会出现零电阻平台,而此时纵向电阻不为零,表现出明显的玻色金属态的特征.研究结果...     

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.     

Anomalous Metallic State Driven by Magnetic Field at the LaAlO3/KTaO3(111) Interface

The origin of the quantum superconductor to metal transition at zero temperature in two-dimensional superconductors is still an open problem, which has caused intensely discussion. Here, we report the observation of a quantum superconductor-to-metal transition in La Al O₃/KTa O₃(111) interface, driven by magnetic field. When a small magnetic field perpendicular to the film plane is applied, the residual saturated resistance is observed,indicating the emergence of an anomalo...