  Quantum spin liquids are exotic phases of quantum matter especially pertinent
to many modern condensed matter systems. Dirac spin liquids (DSLs) are a class
of gapless quantum spin liquids that do not have a quasi-particle description
and are potentially realized in a wide variety of spin $1/2$ magnetic systems
on $2d$ lattices. In particular, the DSL in square lattice spin-$1/2$ magnets
is described at low energies by $(2+1)d$ quantum electrodynamics with $N_f=4$
flavors of massless Dirac fermions minimally coupled to an emergent $U(1)$
gauge field. The existence of a relevant, symmetry-allowed monopole
perturbation renders the DSL on the square lattice intrinsically unstable. We
argue that the DSL describes a stable continuous phase transition within the
familiar Neel phase (or within the Valence Bond Solid (VBS) phase). In other
words, the DSL is an "unnecessary" quantum critical point within a single phase
of matter. Our result offers a novel view of the square lattice DSL in that the
critical spin liquid can exist within either the Neel or VBS state itself, and
does not require leaving these conventional states.
