# The magnetic phase diagram of the frustrated spin chain compound linarite, PbCuSO$_4$(OH)$_2$, as seen by neutron diffraction and $^1$H-NMR

## TL;DR

This study combines neutron diffraction and NMR to map the complex magnetic phase diagram of linarite, revealing intricate magnetic configurations and excitations influenced by anisotropy and Dzyaloshinsky-Moriya interactions.

## Contribution

It provides the first detailed magnetic phase diagram of linarite using combined neutron and NMR techniques, highlighting the role of anisotropy and bound magnon excitations.

## Key findings

- Magnetic moments are quantified across the phase diagram.
- The SDW propagation vector shifts with field and temperature.
- Complex phases near the quasi-saturation field suggest bound two-magnon excitations.

## Abstract

We report on a detailed neutron diffraction and $^1$H-NMR study on the frustrated spin-1/2 chain material linarite, PbCuSO$_4$(OH)$_2$, where competing ferromagnetic nearest neighbor and antiferromagnetic next-nearest neighbor interactions lead to frustration. From the magnetic Bragg peak intensity studied down to 60 mK, the magnetic moment per Cu atom is obtained within the whole magnetic phase diagram for $H \parallel b$ axis. Further, we establish the detailed configurations of the shift of the SDW propagation vector in phase V with field and temperature. Finally, combining our neutron diffraction results with those from a low-temperature/high-field NMR study we find an even more complex phase diagram close to the quasi-saturation field suggesting that bound two-magnon excitations are the lowest energy excitations close to and in the quasi-saturation regime. Qualitatively and semi-quantitatively, we relate such behavior to $XYZ$ exchange anisotropy and contributions from the Dzyaloshinsky-Moriya interaction to affect the magnetic properties of linarite.