Abstract
We consider the competition between the conventional -wave and the triplet Balian-Werthamer or the -phase pairings in doped three-dimensional narrow-gap semiconductors, such as and . When the coupling constants of the two contending channels are comparable, we find a simultaneously time-reversal and parity violating state at low temperatures, which provides an example of a dynamic axionic state of matter. In contradistinction to the time-reversal invariant, topological phase, the state possesses gapped Majorana fermions as surface Andreev bound states, which give rise to an anomalous surface thermal Hall effect. The anomalous gravitational and electrodynamic responses of the state can be described by the vacuum structure, where or .
- Received 11 July 2013
- Revised 22 June 2014
DOI:https://doi.org/10.1103/PhysRevB.90.041301
©2014 American Physical Society