Evidence for antiferromagnetism coexisting with charge order in the trilayer cuprate HgBa$_2$Ca$_2$Cu$_3$O$_{8+ \delta}$

TL;DR

This study provides evidence that antiferromagnetic order coexists with charge order in a trilayer cuprate superconductor, suggesting magnetic interactions play a role in high-temperature superconductivity.

Contribution

First quantum oscillation and Hall effect measurements in the trilayer cuprate HgBa$_2$Ca$_2$Cu$_3$O$_{8+ \delta}$ reveal coexistence of antiferromagnetism and charge order.

Findings

Antiferromagnetic order exists in the inner CuO$_2$ plane.

Charge order is present in the outer CuO$_2$ planes.

Antiferromagnetic metallic state persists deep into the superconducting phase.

Abstract

Multilayered cuprates possess not only the highest superconducting temperature transition but also offer a unique platform to study disorder-free CuO$_2$ planes and the interplay between competing orders with superconductivity. Here, we study the underdoped trilayer cuprate HgBa$_2$Ca$_2$Cu$_3$O$_{8+ \delta}$ and we report the first quantum oscillation and Hall effect measurements in magnetic field up to 88 T. A careful analysis of the complex spectra of quantum oscillations strongly supports the coexistence of an antiferromagnetic order in the inner plane and a charge order in the outer planes. The presence of an ordered antiferromagnetic metallic state that extends deep in the superconducting phase is a key ingredient that supports magnetically mediated pairing interaction in cuprates.