Valleytronics is a technology applied to devices using valley freedom in electrons during crystallization. The former travels through the crystal like a wave. However, in wave vibration energy, a bend (valley) between the peak and the trough is created. It’s like using energy flowing in and out. Using the quantum number that determines this valley is bellitronics.
Bellitronics is expected to be able to realize the low power and large capacity required for next-generation electronic devices, and active research is being conducted recently. A research team at the University of Bombay, India, reported that they realized the valley control of graphene, which was difficult so far, and said that it showed the possibility of success of the technology to realize a calculation speed 1 million times than now.
In the electronics field, spintronics, which has the same degree of freedom as electron rotation called spin, as well as the charge freedom of electrons, is being applied to electronic devices such as hard disks. Belitronics is intended to be used as a new technology following spintronics. Among the band structures that show the relationship between material energy and frequency, it is a technology that has a degree of freedom in where electrons enter a taper-shaped valley that shows the minimum value of the energy band.
In order to realize bellytronics, it is necessary to use a material having valley degrees of freedom, but general materials do not have this. Therefore, research using graphene, a sheet-like material with a honeycomb structure thin at an atomic level with valley degrees of freedom, is being conducted for the bellitronics.
However, graphene has been known to be difficult to control valleys alone due to its unusual metallic state and chiral symmetry. Therefore, the research team came up with a way to use graphene valleys using light.
According to the research team, by adjusting two laser polarizations according to the triangular lattice with graphene, it is possible to break the symmetry between carbon atoms that cause valley polarization and utilize the valley anisotropy space. In this way, information can be recorded effectively, enabling Bellitronics, which theoretically provides computational speed over a million times higher than before. The research team says that one of the most attractive aspects of valley control in graphene is that it is feasible at room temperature, showing the potential for realization of general small general-purpose quantum computers. Related information can be found here.