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arXiv · 2607.03287

Anomalous Structural Response of Quasi-One-Dimensional Antiferromagnetic Metal KMn6Bi5 under high pressure

Hanming Ma·Qingxin Dong·Tong Shi·Xiaoli Ma·Zhongjin Wu·Shaoheng Ruan·Pengtao Yang·Zhaoming Tian·Jianping Sun·Yoshiya Uwatoko·Genfu Chen·Xiaohui Yu·Bosen Wang·Jinguang Cheng
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Abstract

We report high-pressure single-crystal X-ray diffraction measurements on the quasi-one-dimensional (Q1D) antiferromagnetic metal KMn6Bi5 up to 12.5 GPa, revealing the detailed pressure evolution of its atomic coordination environment. We find that the lattice exhibits pronounced anisotropic compressibility-the relative changes in the a and b lattice parameters reach a/a0=0.91 and b/b0 = 0.94 at 12.5 GPa-and a distinct structural anomaly emerges near 11 GPa without any symmetry-breaking. Detailed structural analysis further uncovers an anomalous hardening of the Mn nanotubes between 5 and 11 GPa, followed by a configuration optimization of the Mn/Bi nanotubes around 11 GPa. These features correlate closely with the reported pressure-temperature phase diagram of KMn6Bi5 and compare favorably with the chemical pressure effects induced by substituting K with Na, Rb, or Cs. Our findings provide key microscopic insights into how coordination environment modulation governs the stability of electronic orders in low-dimensional systems.

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Hanming Ma, Qingxin Dong, Tong Shi, Xiaoli Ma, Zhongjin Wu, Shaoheng Ruan, Pengtao Yang, Zhaoming Tian, Jianping Sun, Yoshiya Uwatoko, Genfu Chen, Xiaohui Yu, Bosen Wang, Jinguang Cheng. 2026-07-03. Anomalous Structural Response of Quasi-One-Dimensional Antiferromagnetic Metal KMn6Bi5 under high pressure. https://arxiv.org/abs/2607.03287

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