Vanishing spin stiffness in the spin-1/2 Heisenberg chain for any nonzero temperature

J. M. P. Carmelo, T. Prosen, D. K. Campbell

Whether at zero spin density $m=0$ and finite temperatures $T>0$ the spin stiffness of the spin-$1/2$ $XXX$ chain is finite or vanishes remains an unsolved and controversial issue,…