Inelastic neutron scattering study of magnetic excitations inSr2RuO4

Abstract

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 dxz-and dyz-bands. The shape of the incommensurate signal agrees well with RPA 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 0.4meV.

Magnetic excitations in the metallic single-layer ruthenates Ca2−xSrxRuOSteffens1, Friedt2, Sidis3 et al. 2011Phys. Rev. BSelf Cite

“…The observation of peaks at Q = (0.7,0. 17 This signal thus indicates that the nesting of the α and β band remains intact despite all changes in the crystal structure and in the Fermi surfaces. First-principles calculations 32 come to the conclusion that, apart from the back-folding effect, the α and β sheets of the Fermi surface are only slightly affected by the rotational distortion of the structure.…”

“…This behavior can be compared to that of the incommensurate scattering in Sr 2 RuO 4 , which also indicates a magnetic transition that is not reached at finite temperature. 17 In both cases the blocking of the transition at low temperature may be connected with a reduction in the electrical resistivity. In Ca 1.38 Sr 0.62 RuO 4 the suppression of the phase transition at low temperature may be further related to the thermal expansion anomaly, which, although being much weaker compared to that in Ca 1.8 When using the corresponding equations (2) and (3), the fit of the ferromagnetic component is not satisfactory, contrary to the description of the incommensurate fluctuations.…”

“…The most detailed description is at present available for Sr 2 RuO 4 . 17,18,[20][21][22][23] Furthermore, the bilayer compound Sr 3 Ru 2 O 7 has been investigated. [24][25][26] The excitations in these materials have the character of fluctuations that are both relatively broad in Q and ω.…”

Magnétisme de bande et Supraconductivité : l'apport de la diffusion inélastique des neutrons

“…A l'opposé, les 04003-p. 15 Collection SFN a) b) c) Figure 6. a) Cartographie de l'intensité magnétique pour un transfert d'énergie de 4.1 meV [18]. b) Coupe à énergie constante le long de la direction (1,0,0) au travers du pic incommensurable.…”

“…Les mesures de diffusion inélastique des neutrons non polarisés [17,18] ont confirmé ce scénario en montrant un spectre d'excitations magnétiques dominé à basse énergie par des fluctuations magnétiques 2D au vecteur d'onde q I C = (0.3, 0.3, L) (Fig. 6a).…”