Research Interests
Dr Carbotte’s interests have ranged over several areas of condensed matter theory including the theory of positron annihilation, calculations of the electron-phonon interaction in metals, superconductivity in conventional metals. Superconductors are metals which carry a current without dissipation. This is a very desirable property for making large electromagnets used in medical imaging. New classes of superconductors are discovered every few years. An important class is the cuprates which are the materials that hold the record critical temperature value [Tc] up to about 150 Kelvin. While much is known about the cuprates there remains important questions, such as mechanism and the origin of the pseudogap. Both these topics remain a focus of Dr Carbotte’s research. More recently Fe-based metals have also been found to superconduct and it has become important to study their properties with a view at increasing the value of Tc. Superconductors are not the only metals of importance in technological applications. The electronic industry can also benefit from new semiconducting materials. In 2004, a single sheet of graphite was exfoliated which is a membrane a single atom thick and has amazing unexpected properties. As an example, the motion of the charge carriers in graphene is governed by a relativistic Dirac equation. Their mobility is excellent and many novel applications have been suggested such as elements in display screens. We are studying the properties of graphene under magnetic field and how its properties depend on the coulomb interactions between the electrons. This is important in understanding the interaction of light with the charge oscillations in the graphene sheets. There are also other new materials with different and quite new functionalities. These include a single layer MoS2 which is a direct gap semiconductor with two valleys. It is possible in these materials to excite electrons exclusively from one of the two valleys leaving the others unaffected. This could be very useful in applications to the communication industry .We plan to study their optical properties with an aim at understanding how incident light can be change to a charge current in these systems. All the proposed research involves theoretical studies aimed at better microscopic understanding of the properties of recently discovered materials. The field of Topological Insulator is rapidly becoming very important and has many similarities to graphene as both involve Dirac Fermions. Topological Insulators are insulating in the bulk but have surface states that are metallic and quite stable, as there are protected by topology. These new states could find applications in novel electronics. We plan to study their optical properties.
