Our research group has published a letter in Nature that provides the key to unlocking the secret of superconductivity in 2D thin films of TiSe2. Working in collaboration with the theoretical group of Prof. Antonio CastroNeto and the experimental group of Prof. Kian Ping Loh, we used extremely sensitive control of huge electric fields at ultralow temperatures to drive TiSe2 from a metallic state to superconductivity.
In a usual metal, such as copper or gold, individual electrons repel one another, but in a superconductor electrons prefer to pair together. This exotic state allows superconductors to carry electricity with zero resistance so that just a thin strand of superconducting wire can carry a huge electrical current that can be used, for example, to create the large magnetic field needed for magnetic resonance imaging in hospitals.
Creating the conditions under which electrons pair together is challenging, especially at temperatures that are not extremely cold. For this reason modern research has focussed on how to use electronic states such as the charge density wave, where electrons prefer to crowd together in certain positions in a crystal, to help superconductivity. Our study showed that rapid fluctuations in a charge density in TiSe2 nucleate superconductivity, analogous to how conditions on earth provided just the right conditions for life.
The result is a breakthrough in clearly demonstrating how superconductivity appears at the microscopic scale and adds weight to theories that have suggested that superconductivity in high temperature copper oxide superconductors proceeds by a similar mechanism. Our work may therefore act as a guide to how scientists can build a material that will superconduct at room temperature, supporting technologies such as clean energy distribution and quantum information.
Click here to read the Straits Times article on the above work.
The electric field drives electrons to dance together in TiSe2: On the left hand state the people representing electrons repel one another. By applying electric field, represented here by music, the electrons dance together in certain regions of the crystal where the charge density varies rapidly.