Field-induced soft-mode quantum phase transition in La$_{1.855}$Sr$_{0.145}$CuO$_{4}$

Chang, J.; Christensen, N. B.; Niedermayer, Ch.; Lefmann, K.; Roennow, H. M.; McMorrow, D. F.; Schneidewind, A.; Link, P.; Hiess, A.; Boehm, M.; Mottl, R.; Pailhes, S.; Momono, N.; Oda, M.; Ido, M.; Mesot, J.

Field-induced soft-mode quantum phase transition in La$_{1.855}$Sr$_{0.145}$CuO$_{4}$

Authors

Description

Inelastic neutron-scattering experiments on the high-temperature superconductor La$_{1.855}$Sr$_{0.145}$CuO$_{4}$ reveal a magnetic excitation gap $Δ$ that decreases continuously upon application of a magnetic field perpendicular to the CuO$_2$ planes. The gap vanishes at the critical field required to induce long-range incommensurate antiferromagnetic order, providing compelling evidence for a field-induced soft-mode driven quantum phase transition.