# Antiferromagnetism in RuO$_2$ as $d$-wave Pomeranchuk instability

## TL;DR

This paper computationally investigates antiferromagnetism in RuO$_2$, revealing a $d$-wave Fermi surface modulation linked to a spin-triplet Pomeranchuk instability and a nodal line near the Fermi level.

## Contribution

It identifies a $d$-wave Pomeranchuk instability as the origin of antiferromagnetism in RuO$_2$, connecting band structure features to magnetic ordering.

## Key findings

- Fermi surface exhibits $d$-wave modulation in the antiferromagnetic state
- Presence of a nodal line near the Fermi level influences magnetic instability
- Finite spin conductivity with sign change in the $ab$ plane

## Abstract

We present a computational study of antiferromagnetic transition in RuO$_2$. The rutile structure with the magnetic sublattices coupled by $\pi/2$-rotation leads to a spin-polarized band structure in the antiferromagnetic state, which gives rise to a $d$-wave modulation of the Fermi surface in the spin-triplet channel. We argue a finite spin conductivity that changes sign in the $ab$ plane is expected RuO$_2$ because of this band structure. We analyze the origin of the antiferromagnetic instability and link it to presence of a nodal line close to the Fermi level.