Helicity dependent photocurrent in electrically gated (Bi,Sb)_2Te_3 thin films
Yu Pan, Qing-Ze Wang, Andrew L. Yeats, Timothy Pillsbury, Thomas C. Flanagan, Anthony Richardella, Haijun Zhang, David D. Awschalom, Chao-Xing Liu, Nitin Samarth
Circularly polarized photons are known to generate a directional helicity-dependent photocurrent in three-dimensional topological insulators at room temperature. Surprisingly, the phenomenon is readily observed at photon energies that excite electrons to states far above the spin-momentum locked Dirac cone and the underlying mechanism for the helicity-dependent photocurrent is still not understood. We resolve the puzzle through a comprehensive study of the helicity-dependent photocurrent in (Bi,Sb)_2Te_3 thin films as a function of the incidence angle of the optical excitation, its wavelength, and the gate-tuned chemical potential. Our observations allow us to unambiguously identify the circular photo-galvanic effect as the dominant mechanism for the helicity-dependent photocurrent. Additionally, we use an analytical calculation to relate the directional nature of the photocurrent to asymmetric optical transitions between the topological surface states and bulk bands. The insights we obtain are important for engineering opto-spintronic devices that rely on optical steering of spin and charge currents.
Electrically tunable circular photocurrent via local-field induced symmetry breaking at a metal-MoTe2 interface
National Gravitation Laboratory, MOE Key Laboratory of Fundamental Physical Quantities Measurement, Huazhong University of Science and Technology（引力实验室，教育部物理量基本测量重点实验室，华中科技大学）；School of Physics, Huazhong University of Science and Technology（华中科技大学物理学院）；Kunming Institute of Physics（昆明物理研究所）；Beijing National Laboratory for Condensed Matter Physics（凝聚态物理北京国家实验室；中国科学院物理研究所纳米物理与器件重点实验室）；Key Laboratory for Nanoscale Physics and Devices, Institute of Physics, Chinese Academy of Sciences（中国科学院大学物理科学学院）；School of Physical Sciences, University of Chinese Academy of Sciences
Electrically Induced, Non-Volatile, Metal Insulator Transition in a Ferroelectric Gated MoS$_2$ Transistor
我们证明了一个电诱导的，非易失性的，金属-绝缘体相变的MOS $_2$晶体管。将单晶外延生长的PbZr $_{0.2}$ Ti $_{0.8}$ O $_3$（PZT）置于由薄膜MoS $_2$制成的场效应晶体管的栅极中。当栅极电压施加到该铁电栅控晶体管时，观察到从绝缘体到金属的明显转变，反之亦然。重要的是，当栅极电压关闭时，铁电体中的剩余极化可以将MoS $_2$保持在其原始相，从而提供非易失性状态。因此，金属或绝缘相可以简单地通过向晶体管施加栅极电压来写入、擦除或保留。
Spin qubits with electrically gated polyoxometalate molecules
自旋量子比特为实现量子计算机提供了最有前途的途径之一。半导体量子点的最新结果表明，电控门控方案特别适合于实现一组通用的量子逻辑门。然而，对于这种半导体量子点来说，可扩展到更大数量的量子位仍然是一个问题。相比之下，化学自下而上的方法允许人们产生相同的单位，其中局域自旋代表量子位。分子磁性已经产生了广泛的系统与定制的性能，但分子允许电门控一直缺乏。在这里，我们建议使用聚氧乙烯酸盐[PMo 1/2 O 40（VO）2]q-，其中两个本地化的自旋-1/2可以通过中央核心的电子耦合。通过分子氧化还原电位的电操纵，可以改变核的电荷。通过这种设置，可以实现两个量子位门和量子位读出。
Electrically-gated laser-induced spin dynamics in magneto-electric iron garnet at room temperature
Radboud University Nijmegen（拉德堡德大学）；Institute for Molecules and Materials（分子与材料研究所）；Faculty of Physics, Lomonosov Moscow State University（莫斯科国立大学物理系）；MIREA - Russian Technological University（莫斯科信息俄罗斯国立技术大学）
