Importance of dynamic lattice effects for crystal field excitations in the quantum spin ice candidate Pr₂Zr₂O₇

Journal Article · 15 August 2021 · Physical Review B

DOI: https://doi.org/10.1103/physrevb.104.075125 · OSTI ID:1813342

Xu, Yuanyuan  ^[1]; Man, Huiyuan ^[2]; Tang, Nan ^[2]; Baidya, Santu ^[3]; Zhang, Hongbing ^[3]; Nakatsuji, Satoru  ^[4]; Vanderbilt, David  ^[3]; Drichko, Natalia ^[5]

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1. Johns Hopkins Univ., Baltimore, MD (United States); Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University
2. Johns Hopkins Univ., Baltimore, MD (United States); Univ. of Tokyo, Chiba (Japan)
3. Rutgers Univ., Piscataway, NJ (United States)
4. Johns Hopkins Univ., Baltimore, MD (United States); Univ. of Tokyo, Chiba (Japan); Japan Science and Technology Agency, Saitama (Japan); Univ. of Tokyo (Japan)
5. Johns Hopkins Univ., Baltimore, MD (United States)

We explore dynamic interactions between the crystal lattice and magnetic degrees of freedom in a frustrated magnetic system using the example of a pyrochlore quantum spin-ice candidate Pr₂Zr₂O₇. Using Raman scattering spectroscopy we demonstrate that crystal electric field excitations of Pr3+, which define the magnetic properties of Pr₂Zr₂O₇, cannot be understood within a model of a static lattice. We identify vibronic interactions with a phonon which lead to a splitting of a doublet crystal field excitation at around 55 meV. We also observe an unconventional behavior of a splitting of the non-Kramers ground state doublet of Pr³⁺, revealed by observing excitations to the first excited singlet state $$E$$$^{0}_{g}$$ → A_1g at around 10 meV. The splitting has a strong temperature dependence, where the doublet structure is most prominent between 50 and 100 K, and the weight of one of the components strongly decreases on cooling contrary to simple thermal population tendency. Furthermore, we suggest a static or dynamic deviation of Pr³⁺ from the position in the ideal crystal structure can be the origin of the effect, with the deviation strongly decreasing at low temperatures.

• Research Organization: Johns Hopkins Univ., Baltimore, MD (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0019331
• OSTI ID: 1813342
• Journal Information: Physical Review B, Journal Name: Physical Review B Journal Issue: 7 Vol. 104; ISSN 2469-9950
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English