SCIENCE SPIN-OFFS

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Skyrme insulators: insulators at the brink of superconductivity

Onur Erten, Po-Yao Chang, Piers Coleman, Alexei M. Tsvelik
(Submitted on 23 Jan 2017)

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 3He-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

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, arguing that the observation of a diamagnetic Fermi surface within an insulating bulk can be understood in terms of a Skyrme insulator. Our theory enables us to understand the linear specific heat of SmB

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in terms of a neutral Majorana Fermi sea and leads us to predict that in low fields of order a Gauss, SmB

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will develop a Meissner effect. ll


https://arxiv.org/abs/1701.06582