Magnon interactions in a moderately correlated Mott insulator

Qisi Wang; S Mustafi; E Fogh; N Astrakhantsev; Z He; I Biało; Ying Chan; L Martinelli; M Horio; O Ivashko; N E Shaik; K von Arx; Y Sassa; E Paris; M H Fischer; Y Tseng; N B Christensen; A Galdi; D G Schlom; K M Shen; T Schmitt; H M Rønnow; J Chang

doi:10.1038/s41467-024-49714-y

Magnon interactions in a moderately correlated Mott insulator

Nat Commun. 2024 Jun 24;15(1):5348. doi: 10.1038/s41467-024-49714-y.

Authors

Qisi Wang^{1

2}, S Mustafi³, E Fogh⁴, N Astrakhantsev³, Z He^{5

6}, I Biało^{3

7}, Ying Chan⁸, L Martinelli³, M Horio³, O Ivashko³, N E Shaik⁴, K von Arx³, Y Sassa⁹, E Paris¹⁰, M H Fischer³, Y Tseng¹⁰, N B Christensen¹¹, A Galdi^{12

13}, D G Schlom^{13

14}, K M Shen^{14

15}, T Schmitt¹⁰, H M Rønnow⁴, J Chang¹⁶

Affiliations

¹ Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong, China. [email protected].
² Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland. [email protected].
³ Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland.
⁴ Institute of Physics, École Polytechnique Fedérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland.
⁵ Institute of High Energy Physics, Chinese Academy of Sciences (CAS), 100049, Beijing, China.
⁶ Spallation Neutron Source Science Center (SNSSC), Dongguan, 523803, China.
⁷ AGH University of Krakow, Faculty of Physics and Applied Computer Science, 30-059, Krakow, Poland.
⁸ Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
⁹ Department of Applied Physics, KTH Royal Institute of Technology, SE-106 91, Stockholm, Sweden.
¹⁰ Swiss Light Source, Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland.
¹¹ Department of Physics, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark.
¹² Dipartimento di Ingegneria Industriale, Universita' degli Studi di Salerno, 84084, Fisciano, SA, Italy.
¹³ Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14850, USA.
¹⁴ Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, 14853, USA.
¹⁵ Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, 14853, USA.
¹⁶ Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland. [email protected].

Abstract

Quantum fluctuations in low-dimensional systems and near quantum phase transitions have significant influences on material properties. Yet, it is difficult to experimentally gauge the strength and importance of quantum fluctuations. Here we provide a resonant inelastic x-ray scattering study of magnon excitations in Mott insulating cuprates. From the thin film of SrCuO₂, single- and bi-magnon dispersions are derived. Using an effective Heisenberg Hamiltonian generated from the Hubbard model, we show that the single-magnon dispersion is only described satisfactorily when including significant quantum corrections stemming from magnon-magnon interactions. Comparative results on La₂CuO₄ indicate that quantum fluctuations are much stronger in SrCuO₂ suggesting closer proximity to a magnetic quantum critical point. Monte Carlo calculations reveal that other magnetic orders may compete with the antiferromagnetic Néel order as the ground state. Our results indicate that SrCuO₂-due to strong quantum fluctuations-is a unique starting point for the exploration of novel magnetic ground states.

Grants and funding

Direct Grant 4053613/Chinese University of Hong Kong (CUHK)