Field-induced bound-state condensation and spin-nematic phase in SrCu&lt;sub&gt;2&lt;/sub&gt;(BO&lt;sub&gt;3&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt; revealed by neutron scattering up to 25.9 T

Fogh, Ellen; Nayak, Mithilesh; Prokhnenko, Oleksandr; Bartkowiak, Maciej; Munakata, Koji; Soh, Jian Rui; Turrini, Alexandra A.; Zayed, Mohamed E.; Pomjakushina, Ekaterina; Kageyama, Hiroshi; Nojiri, Hiroyuki; Kakurai, Kazuhisa; Normand, Bruce; Mila, Frédéric; Rønnow, Henrik M.

doi:10.1038/s41467-023-44115-z

Field-induced bound-state condensation and spin-nematic phase in SrCu₂(BO₃)₂ revealed by neutron scattering up to 25.9 T

Fogh E, Nayak M, Prokhnenko O, Bartkowiak M, Munakata K, Soh JR, Turrini AA, Zayed ME, Pomjakushina E, Kageyama H, Nojiri H, Kakurai K, Normand B, Mila F & Rønnow HM

Citation

Fogh, E., Nayak, M., Prokhnenko, O., Bartkowiak, M., Munakata, K., Soh, J. R., … Rønnow, H. M. (2024). Field-induced bound-state condensation and spin-nematic phase in SrCu₂(BO₃)₂ revealed by neutron scattering up to 25.9 T. Nature Communications, 15(1), 442 (10 pp.). https://doi.org/10.1038/s41467-023-44115-z

Persistent URL https://www.dora.lib4ri.ch/psi/islandora/object/psi:58038

In quantum magnetic materials, ordered phases induced by an applied magnetic field can be described as the Bose-Einstein condensation (BEC) of magnon excitations. In the strongly frustrated system SrCu₂(BO₃)₂, no clear magnon BEC could be observed, pointing to an alternative mechanism, but the high fields required to probe this physics have remained a barrier to detailed investigation. Here we exploit the first purpose-built high-field neutron scattering facility to measure the spin excitations of SrCu₂(BO₃)₂ up to 25.9 T and use cylinder matrix-product-states (MPS) calculations to reproduce the experimental spectra with high accuracy. Multiple unconventional features point to a condensation of S = 2 bound states into a spin-nematic phase, including the gradients of the one-magnon branches and the persistence of a one-magnon spin gap. This gap reflects a direct analogy with superconductivity, suggesting that the spin-nematic phase in SrCu₂(BO₃)₂ is best understood as a condensate of bosonic Cooper pairs.