SPIN STIFFNESS IN THE FRUSTRATED HEISENBERG-ANTIFERROMAGNET

We calculate the spin stiffness of the S= 1/2 frustrated Heisenberg an tiferromagnet directly from a general formula which is evaluated in th e Schwinger-boson mean-field approximation. Both Neel and collinear or dering are considered. For collinear ordering, we take the anisotropy of this phase into account, unlike previous approaches. For Neel order ing, a detailed study is made of the finite-size scaling behavior of t he two terms that make up the spin stiffness. The exponents of the sca ling with the system size of the two terms comprising the spin stiffne ss turn out to be identical to those of the unfrustrated case.