Decay and renormalization of a longitudinal mode in a quasi-two-dimensional antiferromagnet

Seung Hwan Do, Hao Zhang, Travis J. Williams, Tao Hong, V. Ovidiu Garlea, J. A. Rodriguez-Rivera, Tae Hwan Jang, Sang Wook Cheong, Jae Hoon Park, Cristian D. Batista, Andrew D. Christianson

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

An ongoing challenge in the study of quantum materials, is to reveal and explain collective quantum effects in spin systems where interactions between different modes types are important. Here we approach this problem through a combined experimental and theoretical study of interacting transverse and longitudinal modes in an easy-plane quantum magnet near a continuous quantum phase transition. Our inelastic neutron scattering measurements of Ba2FeSi2O7 reveal the emergence, decay, and renormalization of a longitudinal mode throughout the Brillouin zone. The decay of the longitudinal mode is particularly pronounced at the zone center. To account for the many-body effects of the interacting low-energy modes in anisotropic magnets, we generalize the standard spin-wave theory. The measured mode decay and renormalization is reproduced by including all one-loop corrections. The theoretical framework developed here is broadly applicable to quantum magnets with more than one type of low energy mode.

Original languageEnglish
Article number5331
JournalNature Communications
Volume12
Issue number1
DOIs
StatePublished - Dec 1 2021

Funding

We thank Shang-Shun Zhang, Jie Xing, and Andrew F. May for useful discussions and Choongjae Won for helping with sample growth. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Science, and Engineering Division. This research used resources at the High Flux Isotope Reactor and Spallation Neutron Source, DOE Office of Science User Facilities operated by the Oak Ridge National Laboratory (ORNL). Access to MACS was provided by the Center for High Resolution Neutron Scattering, a partnership between the National Institute of Standards and Technology and the National Science Foundation under Agreement No. DMR-1508249. The work at Max Planck POSTECH/Korea Research Initiative was supported by Nano Scale Optomaterials and Complex Phase Materials (2016K1A4A4A01922028) and Grant No. 2020M3H4A2084418, through the National Research Foundation (NRF) funded by MSIP of Korea. The work at Rutgers University was supported by the DOE under Grant No. DOE: DE-FG02-07ER46382. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).

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