# Spin Resonance and Magnetic Order in an Unconventional Superconductor

## TL;DR

This paper investigates the interplay between magnetic order and spin resonance in an unconventional d-wave superconductor, revealing that the resonance persists despite static magnetic order, suggesting a specific mode nature.

## Contribution

It demonstrates that spin resonance remains unaffected by magnetic order in a model superconductor, providing insights into the resonance's nature in related materials.

## Key findings

- Spin resonance persists despite magnetic order.
- Resonance likely a longitudinal mode with fluctuating moments.
- Magnetic order does not suppress the spin resonance.

## Abstract

Unconventional superconductivity in many materials is believed to be mediated by magnetic fluctuations. It is an open question how magnetic order can emerge from a superconducting condensate and how it competes with the magnetic spin resonance in unconventional superconductors. Here we study a model d-wave superconductor that develops spin-density wave order, and find that the spin resonance is unaffected by the onset of static magnetic order. This result suggests a scenario, in which the resonance in Nd0.05Ce0.95CoIn5 is a longitudinal mode with fluctuating moments along the ordered magnetic moments.