  In light of the discovery of the long-period radio pulsar PSR J0901-4046, it
is interesting to revisit a question about how the magnetized neutron star
slows down its rotation. In the case of a weak or liquid outer crust, the
mechanism of spin-down becomes unclear because the braking stress cannot then
be transmitted from the surface to the main bulk of the star. We show that even
if the outer crust does not withstand the surface electromagnetic forces
creating the braking torque, the stellar spin-down does not stop, and the
matter rearranges so that the necessary electromagnetic forces form in more
deep and rigid layers capable of withstanding these forces. The spin-down rate
remains the same and corresponds to the transformation of the rotational energy
of the neutron star into the energy of the generated relativistic
electron-positron plasma. The solid iron surface of ultrastrongly magnetized
PSR J0901-4046 appears not to be yielding and withstands the braking stress
without breaking.
