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Charge and spin are two intrinsic attributes of carriers governing almost all of the physical processes and operation principles in materials. Here, we demonstrate the manipulation of electronic and spin states in designed Co-quantum dot/WS2(Co-QDs/WS2) heterostructures by employing a metal–dielectric composite substrate and via scanning tunneling microscope. By repeatedly scanning under a unipolar bias, switching the bias polarity, or applying a pulse through nonmagnetic or magnetic tips, the Co-QDs morphologies exhibit a regular and reproducible transformation between bright and dark dots. First-principles calculations reveal that these tunable characters are attributed to the variation of density of states and the transition of magnetic anisotropy energy induced by carrier accumulation. It also suggests that the metal–dielectric composite substrate is successful in creating the interfacial potential for carrier accumulation and realizes the electrically controllable modulations. These results will promote the exploration of electron–matter interactions in quantum systems and provide an innovative way to facilitate the development of spintronics.

We present a novel method to prepare highly conductive, free-standing, and flexible porous carbon thin films by chemical activation of reduced graphene oxide paper. These flexible carbon thin films possess a very high specific surface area of 2400 m2g–1with a high in-plane electrical conductivity of 5880 S m–1. This is the highest specific surface area for a free-standing carbon film reported to date. A two-electrode supercapacitor using these carbon films as electrodes demonstrated an excellent high-frequency response, an extremely low equivalent series resistance on the order of 0.1 ohm, and a high-power delivery of about 500 kW kg–1. While higher frequency and power values for graphene materials have been reported, these are the highest values achieved while simultaneously maintaining excellent specific capacitances and energy densities of 120 F g–1and 26 W h kg–1, respectively. In addition, these free-standing thin films provide a route to simplify the electrode-manufacturing process by eliminating conducting additives and binders. The synthetic process is also compatible with existing industrial level KOH activation processes and roll-to-roll thin-film fabrication technologies.

Magnetic proximity interaction provides a promising route to manipulate the spin and valley degrees of freedom in van der Waals heterostructures. Here, we report a control of valley pseudospin in the WS2/MoSe2heterostructure by utilizing the magnetic proximity effect of few-layered CrBr3and, for the first time, observe a substantial difference in valley polarization of intra/interlayer excitons under different circularly polarized laser excitations, referred to as chirality-dependent valley polarization. Theoretical and experimental results reveal that the spin-selective charge transfer between MoSe2and CrBr3, as well as between MoSe2and WS2, is mostly responsible for the chiral feature of valley polarization in comparison with the proximity exchange field. This means that a long-distance manipulation of exciton behaviors in multilayer heterostructures can be achieved through spin-selective charge transfer. This work marks a significant advancement in the control of spin and valley pseudospin in multilayer structures.