Abstract
Fifty years after Anderson’s resonating valence-bond proposal, the spin-1/2 triangular-lattice Heisenberg antiferromagnet (TLHAF) remains the ultimate platform to explore highly entangled quantum spin states in proximity to magnetic order. Yb-based delafossites are ideal candidate TLHAF materials, which allow experimental access to the full range of applied in-plane magnetic fields. We perform a systematic neutron scattering study of CsYbSe2, first proving the Heisenberg character of the interactions and quantifying the second-neighbor coupling. We then measure the complex evolution of the excitation spectrum, finding extensive continuum features near the 120°-ordered state, throughout the 1/3-magnetization plateau and beyond this up to saturation. We perform cylinder matrix-product-state (MPS) calculations to obtain an unbiased numerical benchmark for the TLHAF and spectacular agreement with the experimental spectra. The measured and calculated longitudinal spectral functions reflect the role of multi-magnon bound and scattering states. These results provide valuable insight into unconventional field-induced spin excitations in frustrated quantum materials.
| Original language | English |
|---|---|
| Article number | 48 |
| Journal | npj Quantum Materials |
| Volume | 8 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 2023 |
Funding
We thank C. McMillen for assistance with single-crystal X-ray diffraction refinements, J. Keum for assistance with X-ray Laue measurements, U. Nitzsche for technical assistance and B. Schmidt, A. S. Sukhanov and A. Chernyshev for helpful discussions. We acknowledge financial support from the Swiss National Science Foundation, from the European Research Council under the grant Hyper Quantum Criticality (HyperQC), the German Research Foundation (DFG) through the Collaborative Research Center SFB 1143 (project # 247310070), the Austrian Science Fund FWF under project I-4548 and from the European Union Horizon 2020 research and innovation program under Marie Skłodowska-Curie Grant No. 884104. Research at Oak Ridge National Laboratory (ORNL) is supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), Materials Sciences and Engineering Division. This research used the resources of the Spallation Neutron Source, a DOE Office of Science User Facility operated by ORNL. X-ray Laue alignment was conducted at the Center for Nanophase Materials Sciences (CNMS) (CNMS2019-R18) at ORNL, which is a DOE Office of Science User Facility. The pulsed magnetic field magnetometry measurements at National High Magnetic Field Laboratory are supported by the U.S. DOE, Office of Science, via BES program “Science of 100 Tesla”. We thank C. McMillen for assistance with single-crystal X-ray diffraction refinements, J. Keum for assistance with X-ray Laue measurements, U. Nitzsche for technical assistance and B. Schmidt, A. S. Sukhanov and A. Chernyshev for helpful discussions. We acknowledge financial support from the Swiss National Science Foundation, from the European Research Council under the grant Hyper Quantum Criticality (HyperQC), the German Research Foundation (DFG) through the Collaborative Research Center SFB 1143 (project # 247310070), the Austrian Science Fund FWF under project I-4548 and from the European Union Horizon 2020 research and innovation program under Marie Skłodowska-Curie Grant No. 884104. Research at Oak Ridge National Laboratory (ORNL) is supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), Materials Sciences and Engineering Division. This research used the resources of the Spallation Neutron Source, a DOE Office of Science User Facility operated by ORNL. X-ray Laue alignment was conducted at the Center for Nanophase Materials Sciences (CNMS) (CNMS2019-R18) at ORNL, which is a DOE Office of Science User Facility. The pulsed magnetic field magnetometry measurements at National High Magnetic Field Laboratory are supported by the U.S. DOE, Office of Science, via BES program “Science of 100 Tesla”.