Field-induced paramagnons at the metamagnetic transition in Ca1.8Sr0.2RuO4

TL;DR

This study investigates magnetic excitations in Ca1.8Sr0.2RuO4 across the metamagnetic transition, revealing a field-induced shift from antiferromagnetic fluctuations to ferromagnetic order, characterized by the emergence of paramagnons and magnons.

Contribution

It provides the first detailed inelastic neutron scattering analysis of magnetic excitations across the metamagnetic transition in Ca1.8Sr0.2RuO4, highlighting the field-induced evolution of magnetic states.

Findings

Field induces transition from antiferromagnetic fluctuations to ferromagnetic order.

Paramagnons and magnons emerge at high magnetic fields.

High-field phase is intrinsically ferromagnetic.

Abstract

The magnetic excitations in Ca1.8Sr0.2RuO4 were studied across the metamagnetic transition and as a function of temperature using inelastic neutron scattering. At low temperature and low magnetic field the magnetic response is dominated by a complex superposition of incommensurate antiferromagnetic fluctuations. Upon increasing the magnetic field across the metamagnetic ransition, paramagnon and finally well-defined magnon scattering is induced, partially suppressing the incommensurate signals. The high-field phase in Ca1.8Sr0.2RuO4 has, therefore, to be considered as an intrinsically ferromagnetic state stabilized by the magnetic field.