  Despite the apparent ubiquity and variety of quantum spin liquids in theory,
experimental confirmation of spin liquids remains to be a huge challenge.
Motivated by the recent surge of evidences for spin liquids in a series of
candidate materials, we highlight the experimental schemes, involving the
thermal Hall transport and spectrum measurements, that can result in
smoking-gun signatures of spin liquids beyond the usual ones. For clarity, we
investigate the square lattice spin liquids and theoretically predict the
possible phenomena that may emerge in the corresponding spin liquids
candidates. The mechanisms for these signatures can be traced back to either
the intrinsic characters of spin liquids or the external field-driven
behaviors. Our conclusion does not depend on the geometry of lattices and can
broadly apply to other relevant spin liquids.
