Inelastic neutron scattering study of magnetic excitations in Sr₂RuO₄

Magnetic excitations in Sr₂RuO₄ have been studied by inelastic neutron scattering. The magnetic fluctuations are dominated by incommensurate peaks related to the Fermi surface nesting of the quasi-one-dimensional d_xz and d_yz bands. The shape of the incommensurate signal agrees well with random phase approximation calculations. At the incommensurate Q positions the energy spectrum considerably softens upon cooling, pointing to a close magnetic instability: _Sr2RuO₄ does not exhibit quantum criticality but is very close to it. ω/T scaling may be fitted to the data for temperatures above 30 K. Below the superconducting transition, the magnetic response at the nesting signal is not found to change in the energy range down to 0.4 meV.