Neutron diffraction of field-induced magnon condensation in the spin-dimerized antiferromagnet Sr$_{3}$Cr$_{2}$O$_{8}$

TL;DR

This study uses neutron diffraction and magnetostriction measurements to explore magnon condensation in Sr$_{3}$Cr$_{2}$O$_{8}$, revealing its magnetic structure and phase diagram under high magnetic fields.

Contribution

It provides the first detailed neutron diffraction analysis of magnon BEC in Sr$_{3}$Cr$_{2}$O$_{8}$, confirming the XY-antiferromagnetic structure and elucidating the role of dimerization.

Findings

Magnetic structure in BEC phase is XY-antiferromagnetic.

Phase diagram of Sr$_{3}$Cr$_{2}$O$_{8}$ under magnetic field is established.

Dimerization stabilizes the low-temperature crystal structure.

Abstract

In this work, we investigate the evolution and settling of magnon condensation in the spin-1/2 dimer system Sr$_{3}$Cr$_{2}$O$_{8}$ using a combination of magnetostriction in pulsed fields and inelastic neutron scattering in a continuous magnetic field. The magnetic structure in the Bose-Einstein condensation (BEC) phase was probed by neutron diffraction in pulsed magnetic fields up to 39~T. The magnetic structure in this phase was confirmed to be an XY-antiferromagnetic structure validated by irreducible representational analysis. The magnetic phase diagram as a function of an applied magnetic field for this system is presented. Furthermore, zero-field neutron diffraction results indicate that dimerization plays an important role in stabilizing the low-temperature crystal structure.