  We propose an approach to detect the peculiarity of Majorana fermions at the
edges of Kitaev magnets. As is well known, a pair of Majorana edge modes is
realized when a single complex fermion splits into real and imaginary parts
which are, respectively, localized at the left and right edges of a sample
magnet. Reflecting both of this peculiarity of the Majorana fermions and the
ground-state degeneracy caused by the existence of the Majorana edge zero
modes, the spins at the edges of the sample magnet are expected to behave as a
peculiar "free" spin which exhibits a unidirectional magnetization without any
transverse magnetization when applied a sufficiently weak external magnetic
field. For the Kitaev honeycomb model, we obtain the expression of the Majorana
edge magnetization by relying on standard techniques to diagonalize a free
fermion Hamiltonian. The magnetization profile thus obtained indeed shows the
expected behavior. We also elucidate the relation between the Majorana edge
flat band and the bulk winding number from a weak topological point of view.
