Anyon explanation for the absence of divalent-copper EPR in high-temperature superconductors and related insulators

Easy detectability of spin-1/2, orbitally nondegenerate centers by electron paramagnetic resonance follows from the existence of Kramers degeneracy, which is a consequence of time-reversal symmetry. If the spin-1/2 centers in high-temperature superconductors and related insulators are not fermions but are anyons, they will not obey time-reversal symmetry, their spin doublets will be split by inhomogeneous internal local fields, and their EPR may then not be easily detectable. © 1992 The American Physical Society.