A research group from the Rutherford Appleton Laboratory, University of Huddersfield, University of Bristol, and University of Kent has identified a new type of unconventional superconductors.
The atomic-scale crystal structure of LaNiGa2, a material that presents a highly exotic type of superconductivity.
The electron fluid that causes electrical conductivity experiences a drastic re-organization when cooling a superconductor to a temperature lower than its critical temperature. This results in the formation of ‘Cooper pairs’ by the electrons. These Cooper pairs are then condensed into a collective quantum state, thus enabling the occurrence of quantum-mechanical effects. Latest superconductivity research has concentrated on these Cooper pairs’ internal structure.
In an earlier study reported in 2009, three researchers of the present group demonstrated that LaNiC2 was a non-unitary triplet superconductor. The study findings were a surprise because LaNiC2 is not a ferromagnetic. The present research group has demonstrated the exotic superconductivity in another material called LaNiGa2. The group carried out the measurements utilizing the muon spin rotation technique at the Rutherford Appleton Laboratory’s ISIS Facility.
The new superconductor’s crystal structure demonstrates symmetry under inversion and in this way it differs from its cousin, LaNiC2. However, the chemical resemblance of the two compounds indicates that these compounds are two examples of a new class of superconductors, which demonstrate non-unitary triplet pairing albeit they are not ferromagnetic.
In this latest study, the researchers demonstrated that these materials become are magnetized in the presence of an external magnetic field, a phenomenon termed as paramagnetism. This can develop a magnetization in consequence of the magnetic moments of the Cooper pairs themselves.
This means that instead of depending on some pre-existing magnetization, the Cooper pairs’ magnetic moments generate the magnetism essential for their energetically favorable magnetization, thus enabling non-unitary triplet pairing to elevate itself by its bootstraps. This may be a superconducting analogue of the mechanism that develops magnetism in ferromagnetic metals. A corroboration of this event would be great as it is a new type of magnetism created by superconductivity.
The finding of a new type of unconventional superconductors is an unusual event. Knowing the mechanism behind this highly-exotic pairing structure is a challenge to be solved. There will also be a competition to discover more instances of this family and more experimental proofs of this unusual phenomenon will be obtained using other techniques.