Is it possible to tidally lock a neutron star? As I know, neutron stars are almost perfect sphere and no net moments, does it mean it is not possible to tidally lock it?
 A: This article may solve the question that you asked,
https://ui.adsabs.harvard.edu/abs/1992ApJ...400..175B/abstract
Title: Tidal Interactions of Inspiraling Compact Binaries
Authors: Bildsten, Lars;  Cutler, Curt
Abstract: We discuss the tidal interaction in neutron star-neutron star and neutron star-black hole binaries and argue that they will not be tidally locked during the gravitational inspiral. More specifically, we show that, for inspiraling neutron stars of mass greater than about 1.2 solar mass, the shortest possible tidal synchronization time exceeds the gravitational decay time, so that the neutron star cannot be tidally locked prior to tidal disruption, regardless of its internal viscosity. For smaller mass neutron stars, an implausibly large kinematic viscosity - nearly the speed of light times the stellar radius - is required for tidal locking. We also argue that the mass transfer which occurs when the neutron star reaches the tidal radius will be unstable in neutron star-black hole binaries, and the instability will destroy the neutron star in a few orbital periods. The implications of our work for the detection of these sources by LIGO and other gravitational wave observatories and for the gamma-ray burst scenarios of Paczynski (1986, 1991) are discussed.
A: If a neutron star were a perfect sphere with a monopole moment and zero quadrupole, etc., moments, it would be impossible to observe its rotation.  For example, observe the rotation of Earth's roundest object (whose rotational symmetry is broken by its crystalline structure).
We are able to observe that neutron stars rotate.  Therefore neutron stars have nonzero moments of inertia and are subject to tidal locking.  However it might take a very long time.  A commenter links to a paper on the subject.
