  The conformal weights of spherical twist operators at non--zero (Euclidean)
chemical potential are computed for free Dirac fields in arbitrary dimensions.
An image technique, equivalent to replicas, is again used to obtain the
$n$--fold cover quantities. The proof of a conjecture made by Bueno, Myers and
Witczac--Krempa regarding the relation between the conformal weights and a
corner coefficient in the R\'enyi entropy, given before for scalar fields, is
extended to the fermion case. The variation of the weights with chemical
potential indicates phase changes.
