Skyrme Insulators: Insulators at the Brink of Superconductivity

• Published in: Physical review letters 2017-08, Vol.119 (5), p.057603-057603, Article 057603
• Main Authors: Erten, Onur, Chang, Po-Yao, Coleman, Piers, Tsvelik, Alexei M
• Format: Article
• Language: English
• Subjects: CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.119.057603

Current theories of superfluidity are based on the idea of a coherent quantum state with topologically protected quantized circulation. When this topological protection is absent, as in the case of ^{3}He-A, the coherent quantum state no longer supports persistent superflow. Here, we argue that the loss of topological protection in a superconductor gives rise to an insulating ground state. We specifically introduce the concept of a Skyrme insulator to describe the coherent dielectric state that results from the topological failure of superflow carried by a complex-vector order parameter. We apply this idea to the case of SmB_{6}, arguing that the observation of a diamagnetic Fermi surface within an insulating bulk can be understood as a realization of this state. Our theory enables us to understand the linear specific heat of SmB_{6} in terms of a neutral Majorana Fermi sea and leads us to predict that in low fields of order a Gauss, SmB_{6} will develop a Meissner effect.