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arXiv 2602.16899cond-mat.str-el
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BaFe₂S₃的基态:晶格与自旋动力学

Ground State of BaFe2S3 from Lattice and Spin Dynamics

Université Paris-Saclay(巴黎萨克雷大学);CNRS(法国国家科学研究中心);Laboratoire de Physique des Solides(固体物理实验室);Synchrotron SOLEIL(SOLEIL同步辐射中心);Institut Laue-Langevin(朗之万研究所);CNRS-CEA(法国国家科学研究中心-法国原子能和替代能源委员会);Laboratoire Léon Brillouin(莱昂·布里渊实验室);CEA(法国原子能和替代能源委员会);SPEC(物质环境与状态物理研究部);Institut Néel(内勒研究所)

Y. Oubaid, S. Deng, NS. Dhami, M. Verseils, D. Bounoua, A. Forget, D. Colson, P. Foury-Leylekian, M. B. Lepetit, V. Balédent

AI总结:

研究BaFe₂S₃中晶格对称性、声子与磁性相互作用,揭示低温下晶格对称性降低及磁有序机制,发现磁动态关联驱动结构不稳定。

摘要:

我们通过极化同步辐射红外光谱、杂化功能密度泛函理论计算和非弹性中子散射,研究了准一维梯状化合物BaFe₂S₃中晶格对称性、声子和磁性之间的相互作用。晶格动力学分析表明,低温下晶体对称性低于先前提出,与P1空间群一致。几种红外活性声子模式在结构转变温度T_S≈125-130 K和奈尔温度T_N≈95 K处表现出显著异常。第一性原理计算显示,受T_S影响的模式主要涉及调节磁交换路径的位移。中子散射显示,在T_N以下,磁序为三维、长程且静态。在T_N和T_S之间,系统表现出三维短程动态磁关联,这些关联在T_S以上消失。因此,结构转变与磁振荡的起始而非静态磁序相关。我们的结果表明,短程动态磁关联足以驱动静态结构不稳定,提供了一种磁驱动机制,类似于铁基122家族,但在此准一维Mott系统中实现。这些发现突显了铁基超导体中磁弹性耦合在非它inerant区域的重要性。

英文摘要:

We investigate the interplay between lattice symmetry, phonons, and magnetism in the quasi-one-dimensional ladder compound BaFe$_2$S$_3$ by combining polarized synchrotron infrared spectroscopy, hybrid-functional density functional theory calculations, and inelastic neutron scattering. Lattice-dynamics analysis reveals that the crystal symmetry is lower than previously proposed and is consistent with a $P1$ space group at low temperature. Several infrared-active phonon modes exhibit pronounced anomalies at both the structural transition temperature $T_S \approx 125$--$130$~K and the Néel temperature $T_N \approx 95$~K. First-principles calculations show that the modes affected at $T_S$ predominantly involve displacements that modulate magnetic exchange pathways. Neutron scattering demonstrates that below $T_N$ the magnetic order is three-dimensional, long-ranged, and static. Between $T_N$ and $T_S$, the system displays three-dimensional short-range dynamic magnetic correlations, which disappear above $T_S$. The structural transition thus coincides with the onset of magnetic fluctuations rather than with static magnetic order. Our results indicate that short-range, dynamical magnetic correlations are sufficient to drive a static structural instability, providing a magnetically driven mechanism reminiscent of the iron-pnictide 122 family, yet realized here in a quasi-one-dimensional Mott system. These findings highlight the central role of magnetoelastic coupling in iron-based superconductors beyond the itinerant regime.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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