The deconfined quantum critical point (DQCP) represents a paradigm shift in quantum matter studies, presenting a “beyond Landau” scenario for order–order transitions. Its experimental realization, however, has remained elusive. Using high-pressure 11 B nuclear magnetic resonance measurements on the quantum magnet SrCu 2 (BO 3 ) 2 , we here demonstrate a magnetic-field induced plaquette-singlet to antiferromagnetic transition above 1.8 GPa at a notably low temperature, T c ≃ 0.07 K. First-order signatures of the transition weaken with increasing pressure, and we observe quantum critical scaling at the highest pressure, 2.4 GPa. Supported by model calculations, we suggest that these observations can be explained by a proximate DQCP inducing critical quantum fluctuations and emergent O(3) symmetry of the order parameters. Our findings offer a concrete experimental platform for the investigation of the DQCP.

中文翻译：

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SrCu 2 (BO 3 ) 2 中的近似解禁量子临界点

解禁量子临界点（DQCP）代表了量子物质研究的范式转变，为有序-有序转变提供了“超越朗道”的场景。然而，它的实验实现仍然难以捉摸。使用高压11B 量子磁体 SrCu 的核磁共振测量 2 （博 3 ） 2 ，我们在这里展示了磁场诱导的血小板单线态到反铁磁的转变 1.8 GPa 在极低的温度下， 时间 C ≃ 0.07 K. 转变的一阶特征随着压力的增加而减弱，我们在最高压力下观察到量子临界缩放， 2.4 GPa。在模型计算的支持下，我们认为这些观察结果可以通过引起临界量子涨落和阶参数的涌现 O(3) 对称性的近似 DQCP 来解释。我们的研究结果为 DQCP 的研究提供了一个具体的实验平台。