Superconducting puddles in electron gas
doi:10.1038/nindia.2013.58 Published online 29 April 2013
Researchers have gained new insights into the physical phenomena occurring in two-dimensional electron gases (2DEGs) that form at the interface between two insulating oxides1 . These insights will be useful for studying the fundamental properties of low-dimensional superconductors.
The formation of 2DEGs at interfaces between insulating oxides has attracted considerable interest because such 2DEGs exhibit interesting properties that are suitable for various applications. In particular, 2DEGs at oxide interfaces are interesting systems for studying quantum phase transitions that occur between different quantum states. The telltale indicator of a quantum phase transition is a transition from a superconducting state to an insulating state in two dimensions. This phenomenon has been debated for a long time with contrasting results having being obtained; a clear picture of it has yet to emerge.
To throw new light on the physics of 2DEGs, the researchers applied a magnetic field perpendicular to a superconducting 2DEG forming at the interface between two insulating oxides (LaTiO3 and SrTiO3). This caused the system to switch to a weakly localized metal. This transition destroyed the superconductivity, giving rise to 2DEGs with superconducting puddles. The study found that intra- and inter-puddle physics emerged, which were affected differently by the application of two magnetic fields.
The researchers say that their study opens the way to explore the new physics of disordered superconductors.
- Biscaras, J. et al. Multiple quantum criticality in a two-dimensional superconductor. Nat. Mater. (2013) doi: 10.1038/nmat3624 10.1038/nmat3624