Spectroscopic Demarcation of Emergent Photons and Spinons in a Dipolar-Octupolar Quantum Spin Liquid

Gao, Bin [Rice University, Houston, TX (United States)] (ORCID:0000000228532362); Zhou, Zhengbang [University of Toronto, ON (Canada)]; Zhang, Tingjun [Rice University, Houston, TX (United States)] (ORCID:0009000305847921); Podlesnyak, Andrey A. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000193666319); Cheong, Sang-Wook [Rutgers University, Piscataway, NJ (United States)]; Kim, Yong Baek [University of Toronto, ON (Canada)]; Dai, Pengcheng [Rice University, Houston, TX (United States)] (ORCID:0000000260883170)

doi:10.1103/svt2-m3pp

DOE OSTI · 3384908

Spectroscopic Demarcation of Emergent Photons and Spinons in a Dipolar-Octupolar Quantum Spin Liquid

Gao, Bin [Rice University, Houston, TX (United States)] (ORCID:0000000228532362)·Zhou, Zhengbang [University of Toronto, ON (Canada)]·Zhang, Tingjun [Rice University, Houston, TX (United States)] (ORCID:0009000305847921)·Podlesnyak, Andrey A. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000193666319)·Cheong, Sang-Wook [Rutgers University, Piscataway, NJ (United States)]·Kim, Yong Baek [University of Toronto, ON (Canada)]·Dai, Pengcheng [Rice University, Houston, TX (United States)] (ORCID:0000000260883170)

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Abstract

The identification of fractionalized excitations in quantum spin liquids (QSLs) remains a central challenge in condensed matter physics. In dipolar-octupolar (DO) pyrochlores, such as Ce 2⁢ Zr 2 ⁢O 7 , the candidate 𝜋-flux quantum spin ice (QSI) state is predicted to host both gapless emergent photons and a continuum of spinons. However, resolving these modes at zero field is complicated by their spectral overlap and the presence of nonmagnetic scattering near zero energy. Here, in this study, we report neutron scattering experiments on Ce 2 ⁢Zr 2 ⁢O 7 under a magnetic field along the [1, 1, 1] direction. In contrast to previous unpolarized studies at zero field that relied on high-temperature subtraction, we use a same-temperature high-field subtraction protocol to isolate the photon and spinon modes. Leveraging the selective coupling of the magnetic field to the dipolar degrees of freedom, we demonstrate the spectroscopic demarcation of these excitations. We observe that weak fields (≈ 0.15 T) suppress the low-energy photon weight while leaving the high-energy spinon continuum robust, albeit hardened. Our results, supported by gauge mean-field theory and exact diagonalization calculations, provide strong evidence for the 𝜋-flux QSI state and introduce a powerful field-tuning protocol for investigating DO-QSLs.

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Gao, Bin [Rice University, Houston, TX (United States)] (ORCID:0000000228532362), Zhou, Zhengbang [University of Toronto, ON (Canada)], Zhang, Tingjun [Rice University, Houston, TX (United States)] (ORCID:0009000305847921), Podlesnyak, Andrey A. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000193666319), Cheong, Sang-Wook [Rutgers University, Piscataway, NJ (United States)], Kim, Yong Baek [University of Toronto, ON (Canada)], Dai, Pengcheng [Rice University, Houston, TX (United States)] (ORCID:0000000260883170). 2026-06-23. Spectroscopic Demarcation of Emergent Photons and Spinons in a Dipolar-Octupolar Quantum Spin Liquid. https://doi.org/10.1103/svt2-m3pp

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