Spin stiffness of frustrated Heisenberg antiferromagnets: Finite-size scaling

We calculate the spin stiffness of the S=1/2 frustrated Heisenberg antiferromagnet on finite square lattices by means of the Schwinger-boson approach. Comparison with recent exact numerical results reveals that the observed lack of scaling with lattice size for intermediate to large frustration cannot be taken as an indication of absence of N\'eel order. This lack of scaling is already apparent for small frustration and is a finite-lattice effect. Our results also indicate that the expected behavior is regained for larger lattices than those considered in numerical studies.