Spin gap and L modulated intensity at the low-energy incommensurate magnetic fluctuations in the superconducting state of Sr2RuO4

TL;DR

This study combines neutron scattering and RPA calculations to explore low-energy magnetic fluctuations in Sr2RuO4, revealing a spin gap and L-modulated intensity that suggest horizontal line nodes in the superconducting gaps.

Contribution

It provides new experimental and theoretical insights into the magnetic fluctuations and gap structure of Sr2RuO4 in the superconducting state.

Findings

Observation of a spin gap at the incommensurate wave vector below Tc

L modulated intensity of magnetic fluctuations in the superconducting state

Indication of horizontal line nodes in the superconducting gaps

Abstract

Low-energy incommensurate (IC) magnetic fluctuations in the multiband superconductor Sr$_2$RuO$_4$ is investigated by high-resolution inelastic neutron scattering measurements and random phase approximation (RPA) calculations. Below $T_\text{c}$, the substantial spin gap is observed at $\mathbf{Q}_\text{IC}=(0.3, 0.3, L)$ where the quasi-one-dimensional $\alpha$ and $\beta$ sheets consisting of the Fermi surfaces are in good nesting conditions. $L$ modulated intensity of the low-energy IC magnetic fluctuations and our RPA calculations indicate that the superconducting gaps regarding the $\alpha$ and $\beta$ sheets have the horizontal line nodes.