D. Schmeltzer et Ar. Bishop, COLLAPSE OF THE SPIN GAP WITH PRESSURE IN SPIN-LADDER COMPOUNDS, Physical review. B, Condensed matter, 58(10), 1998, pp. 5905-5907
We introduce a model of weakly coupled spin ladders using a decomposit
ion into triplet and singlet Majorana fermions. We show that a weak co
upling between the ladders causes the triplet gap to vanish. Assuming
that pressure enhances the interladder coupling, we find that the trip
let gap vanishes with increased pressure. We suggest that this is the
explanation of recent nuclear magnetic resonance experimental data in
superconducting spin-ladder compounds such as Sr2Ca12Cu24O41.