arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2004.00661cond-mat.str-el
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Ba $_3$ LaRu $_2$ O $_9$中选轨Mott态的分子水平实现

Realization of the orbital-selective Mott state at the molecular level in Ba$_3$LaRu$_2$O$_9$

Q. Chen, A. Verrier, D. Ziat, A. J. Clune, R. Rouane, X. Bazier-Matte, G. Wang, S. Calder, K. M. Taddei, C. R. dela Cruz, A. I. Kolesnikov, J. Ma, J. -G. Cheng,… 展开作者

Q. Chen, A. Verrier, D. Ziat, A. J. Clune, R. Rouane, X. Bazier-Matte, G. Wang, S. Calder, K. M. Taddei, C. R. dela Cruz, A. I. Kolesnikov, J. Ma, J. -G. Cheng, Z. Liu, J. A. Quilliam, J. L. Musfeldt, H. D. Zhou, A. A. Aczel

摘要:

近年来,基于重过渡金属的分子磁体在寻求新的磁性方面引起了人们极大的兴趣。对于每个分子具有奇数个价电子的系统,通常分别在双交换或准分子轨道极限中预期高或低分子自旋状态。在这项工作中,我们使用体积表征,μ子自旋弛豫,中子衍射和非弹性中子散射,以确定一个罕见的中间自旋3/2每二聚体状态的6 H-钙钛矿钡$_3$ LaRu $_2$ O $_9$,不能被理解在一个双交换或准分子轨道图片,而是产生从轨道选择性莫特绝缘行为在分子水平上。我们的测量还表明,对于这些分子自旋3/2自由度,共线条纹磁序低于$T_N$ = 26(1)K,这与具有显著次近邻面内交换的理想三角形晶格的预期一致。最后,我们提出了中子衍射和拉曼散射数据下施加的压力,揭示了低洼的结构和自旋态转变在适度的压力P $\le$ 1 GPa,这突出了竞争的能量尺度之间的微妙平衡,在这个系统。

英文摘要:

Molecular magnets based on heavy transition metals have recently attracted significant interest in the quest for novel magnetic properties. For systems with an odd number of valence electrons per molecule, high or low molecular spin states are typically expected in the double exchange or quasi-molecular orbital limits respectively. In this work, we use bulk characterization, muon spin relaxation, neutron diffraction, and inelastic neutron scattering to identify a rare intermediate spin-3/2 per dimer state in the 6H-perovskite Ba$_3$LaRu$_2$O$_9$ that cannot be understood in a double exchange or quasi-molecular orbital picture and instead arises from orbital-selective Mott insulating behavior at the molecular level. Our measurements are also indicative of collinear stripe magnetic order below $T_N$ = 26(1) K for these molecular spin-3/2 degrees-of-freedom, which is consistent with expectations for an ideal triangular lattice with significant next nearest neighbor in-plane exchange. Finally, we present neutron diffraction and Raman scattering data under applied pressure that reveal low-lying structural and spin state transitions at modest pressures P $\le$ 1 GPa, which highlights the delicate balance between competing energy scales in this system.

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