Physicists uncover hidden Zeeman field in odd-parity magnets in analytical model
Researchers revealed that intrinsic time-reversal symmetry breaking enables robust field-free topological superconductivity in odd-parity magnets.
Physicists from the High Magnetic Field Laboratory of the Hefei Institutes of Physical Science and the Hong Kong University of Science and Technology have demonstrated that odd-parity magnets universally host a hidden Zeeman field aps.org
Physical Review Lettersaps.orgOpen source ↗. The study, published in Physical Review Letters, showed that this internal field arises directly from the intrinsic breaking of time-reversal symmetry inherent to magnetic order. Using an analytical model of an f-wave magnet on a triangular lattice, the researchers explained how this phenomenon reshapes the material's band structure and enables topological superconductivity without requiring external magnetic fields.
Mechanism of band structure reshaping
Conventional approaches to topological superconductors rely on external magnetic fields, which often suppress superconductivity and leave topological phases vulnerable to disorder. In odd-parity magnets, the band structure is shaped by two distinct phenomena: nonrelativistic spin splitting and the hidden Zeeman field. The nonrelativistic spin splitting originates microscopically from an emergent gauge field, manifesting as a real-space spin loop-current order. Meanwhile, the hidden Zeeman field directly lifts Kramers degeneracy at time-reversal-invariant momenta and induces Zeeman splitting reaching hundreds of millielectronvolts.
Stabilization of topological phases
Self-consistent mean-field calculations revealed that electron-volt-scale nonrelativistic spin splitting locks spin polarization perpendicular to the hidden Zeeman field. This interaction generates a protection mechanism analogous to Ising superconductivity, allowing conventional s-wave superconductivity to coexist with the strong internal Zeeman field beyond the Pauli limit. By introducing s-wave pairing into this system, the team engineered several topological superconducting phases. According to the researchers, these phases host distinct Majorana boundary modes, including unidirectional Majorana edge states and Majorana flat bands, establishing odd-parity magnets as a platform for fault-tolerant quantum computing systems.
