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Opening a new way of handling valleys with acoustic methods – ScienceDaily


Researchers at the Center for the Theoretical Physics of Complex Systems (PCS) within the Institute of Basic Sciences (IBS, South Korea) and colleagues reported a new phenomenon called Valley Acoustoelectric Effect, which takes place in 2D materials similar to graphene. . This survey is published in Physical letters for review and brings new insights into the study of valleytronics.

In acoustoelectronics, surface acoustic waves (SAW) are used to generate electric currents. In this study, a group of theoretical physicists modeled the propagation of SAW in emerging 2D materials such as single-layer molybdenum disulfide (MoS2). SAW pulls MoS2 electrons (and holes), creating electrical current with conventional and non-conventional components. The latter is composed of two contributions: the flow-based flow and Hall's flow. The first is dependent on direction, it is related to so-called valleys – local energy minima of electrons – and is similar to one of the mechanisms that explain the photovoltaic effects of 2D materials exposed to light. The other is due to the specific effect (strawberry stage) that affects the speed of these electrons traveling as a group and causing interesting phenomena such as anomalous and quantum Hall effect.

The group analyzed the properties of the acoustoelectric current, which showed that it is possible to independently measure conventional, bending and hollow currents. This allows the simultaneous use of optical and acoustic techniques to control the spread of charge carriers in new 2D materials, creating new logical devices.

Researchers are interested in controlling the physical properties of these ultra thin systems, especially those of the electron moving freely in two dimensions, but are tightly closed in the third. By limiting the parameters of the electrons, especially the motion of motion, the speeds and the valleys, it will be possible to investigate technologies that go beyond silicon electronics. MoS2 has, for example, two distretional valleys that could be used in the future to store and process bits, which would be the ideal material for exploring valleytronics.

"Our theory opens a way of manipulating the valley transmissions with acoustic methods, thus extending the usefulness of valleytronic effects on acoustoelectronic devices," explains Ivan Savenko, head of the group for the cooperation of light in nanostructures on PCS.

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