Semi - Dirac Metals | 06 Nov 2019

Researchers from the Indian Institute of Technology - Bombay have discovered special properties in a class of materials called “semi-dirac metals”.

In general, metals are good conductors of electricity.
A key aspect that decides the quality of conduction is the way energy depends on the momentum of electrons.
Dirac metals differ from normal metals in that the energy depends linearly on the momentum of electrons. This difference is also responsible for their unique properties.
Semi-Dirac metals behave like Dirac metals in one direction and like normal metals in the perpendicular directions (since their microscopic structure is different along the two directions).
Examples of semi-dirac metals are systems such as TiO₂/V₂O₃ nanostructures (Oxides of Titanium and Vanadium).

The direction-dependence of microscopic properties gives Semi - Dirac material special optical properties.
- Semi-Dirac materials have very high optical conductivity of electromagnetic waves (light waves). These waves are of a specific frequency and a specific polarisation.
- Optical conductivity is a measure of the opacity offered by the material to the passage of light through it.
  - Semi - Dirac materials would be transparent to light of a given frequency and polarisation when it is incident along a particular direction.
  - These materials would be opaque to the same light when it falls on it from a different direction.
  - There are many known applications for transparent conducting films – the common example being touch screens used in mobiles.
The material possesses interesting thermoelectric properties.
- Thermoelectricity is a clean energy technology that uses waste heat to produce electricity typically in low power applications.
- This technology is used in efficient cars, where it is used to keep the lights on and to warm seats.