Anisotropy in the Antiferromagnetic Spin Fluctuations of Sr2RuO4

TL;DR

This study reveals that in Sr2RuO4, incommensurate spin fluctuations exhibit c-axis anisotropy, supporting theories that such anisotropic fluctuations may contribute to its p-wave superconductivity.

Contribution

The paper provides the first experimental evidence of c-axis anisotropy in incommensurate spin fluctuations in Sr2RuO4 using neutron scattering.

Findings

Incommensurate spin fluctuations have a c-axis anisotropic factor of ~2.8.

Results support theories linking anisotropic spin fluctuations to p-wave superconductivity.

Neutron scattering confirmed the presence of incommensurate fluctuations near q=(1/3, 1/3, 0).

Abstract

It has been proposed that Sr_2RuO_4 exhibits spin triplet superconductivity mediated by ferromagnetic fluctuations. So far neutron scattering experiments have failed to detect any clear evidence of ferromagnetic spin fluctuations but, instead, this type of experiments has been successful in confirming the existence of incommensurate spin fluctuations near q=(1/3 1/3 0). For this reason there have been many efforts to associate the contributions of such incommensurate fluctuations to the mechanism of its superconductivity. Our unpolarized inelastic neutron scattering measurements revealed that these incommensurate spin fluctuations possess c-axis anisotropy with an anisotropic factor \chi''_{c}/\chi''_{a,b} of \sim 2.8. This result is consistent with some theoretical ideas that the incommensurate spin fluctuations with a c-axis anisotropy can be a origin of p-wave superconductivity of this material.