Two-Dimensional Incommensurate Magnetic Fluctuations in Sr2(Ru0.99Ti0.01)O4

We investigate the imaginary part of the wave vector dependent dynamic spin susceptibility in Sr₂(Ru_0.99Ti_0.01)O₄ as a function of temperature using neutron scattering. At T=5 K, two-dimensional incommensurate (IC) magnetic fluctuations are clearly observed around Q_IC=(0.3,0.3,L) up to approximately 60 meV energy transfer. We find that the IC excitations disperse to ridges around the (π,π) point. Below 50 K, the energy and temperature dependent excitations are well described by the phenomenological response function for a Fermi liquid system with a characteristic energy of 3.9(1) meV. Although the characteristic energy scale of the magnetic fluctuations, \hbarω_SF, is slightly suppressed by the Ti-doping, the wave vector dependence of the IC magnetic fluctuations in Sr₂(Ru_0.99Ti_0.01)O₄ is very similar to that in the Fermi liquid state of the parent compound, Sr₂RuO₄.