  The main challenge in the recent demonstration of conventional magnon
blockade is to increase the nonlinearity of the system especially in comparison
with the dissipation channels. One can consider the Kerr nonlinearity through
which magnon blockade in a cavity magnonic system is possible provided that the
Kerr nonlinearity is much stronger than the cavity and magnonic mode
dissipation rates. In the present contribution, we consider a PT-symmetric
cavity magnonic system and study the effect of PT-symmetric phase on the magnon
statistics and hence magnon blockade. We show that the PT-symmetric phase,
which is achievable by properly selecting the system parameters, can relax the
requirement of large Kerr nonlinearity such that a perfect magnon blockade can
be easily obtained even under a small value of Kerr nonlinearity. Surprisingly,
although there is no photonic Kerr nonlinearity in the scheme, photon blockade
can also occur simultaneously with magnon blockade. This result is arising from
the PT-symmetric phase which can generate an effective photonic Kerr
nonlinearity.
