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arXiv · 2607.10877

Pinwheel-shaped bound triplet pairs in the magnetization plateaus of SrCu$_2$(BO$_3$)$_2$

Igor Vinograd·Philippe Corboz·Steffen Krämer·Yanan Li·Frédéric Mila·Hiroshi Kageyama·Masashi Takigawa·Mladen Horvatić
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Abstract

The sequence of magnetization plateaus at 1/8, 2/15, 1/6, 1/4, 1/3, 2/5, and 1/2 of the saturation observed in SrCu$_2$(BO$_3$)$_2$ remained a puzzle until tensor-networks-based numerical simulations suggested that the low-magnetization plateaus are stabilized as Wigner crystals of spin-2 bound states, and not as one of the standard configurations (semiclassical up-down, or crystals of triplets). We report on $^{63,65}$Cu nuclear magnetic resonance spectra up to 41.9 T: Based on constraints deduced from the 1/3 plateau, we show that the spectra in the 1/8 and 2/15 plateaus indeed agree with the prediction for the spin-2 bound states, while being incompatible with a crystal of triplets. This adds the formation of Wigner crystals of bound states as an alternative fundamental paradigm in the theory of magnetization plateaus.

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Igor Vinograd, Philippe Corboz, Steffen Krämer, Yanan Li, Frédéric Mila, Hiroshi Kageyama, Masashi Takigawa, Mladen Horvatić. 2026-07-12. Pinwheel-shaped bound triplet pairs in the magnetization plateaus of SrCu$_2$(BO$_3$)$_2$. https://arxiv.org/abs/2607.10877

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