Modeling of Weyl Semimetal Electrical Devices

The main goal of this project is to exploit the peculiar physics of a class of topological material, the Weyl semimetals, for new electrical devices. These materials, due to their unusual band structure (which is gapped except at some isolated points, called Weyl nodes) have been shown to exhibit interesting properties like a huge magneto-resistance at cryogenic temperatures, and a set of different transport mechanisms that can be exploited for several purposes. Applications-wise, the focus of this work is on two possible device implementations: a Weyl semimetal amplifier and an oscillator. These two device concepts are designed to work under low power and cryogenic conditions, which make them highly suitable for quantum-computing applications. Concerning the oscillator, the work mainly focuses on the possibility of achieving a coherent output field and the description of the working conditions that are needed to fulfill that goal. The main components of the device concept are a Weyl semimetal slab, coupled with a charge sensing device. The Weyl semimetal slab is subjected to crossed magnetic and electric field: this condition is able to produce an exotic trajectory for the electrons inside the slab, that translates into the generation of an oscillating electric field. The charge sensing device, in its simplest configuration, can be simply a standard transistor or, even better, a quantum dot. The work on the amplifier instead is based on a device model consisting of a superconductive gating of a Weyl semimetal channel and focuses on the understanding and modelling of the underlying physics, in order to have a clear perspective of its performances, making possible to compare its behavior to the existing competing technologies. In conclusion, the device simulations performed in this work have elucidated the potential of Weyl semimetals for novel electron devices. The proposed amplifier, in particular, is in simulations able to operate with an extreme reduction of DC power, upwards to 100 times lower than standard HEMT technology, with comparable power gain, highlighting the strong promise of this class of topological materials.