arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2004.11651cond-mat.mtrl-scicond-mat.str-elcond-mat.supr-con
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Ba2CuO3 +δ的X射线吸收光谱和共振非弹性X射线散射研究

Crystalline and magnetic structure of Ba2CuO3+δ investigated by x-ray absorption spectroscopy and resonant inelastic x-ray scattering

Roberto Fumagalli, Abhishek Nag, Stefano Agrestini, Mirian Garcia-Fernandez, Andrew C. Walters, Davide Betto, Nicholas B. Brookes, Lucio Braicovich, Ke-Jin Zhou… 展开作者

Roberto Fumagalli, Abhishek Nag, Stefano Agrestini, Mirian Garcia-Fernandez, Andrew C. Walters, Davide Betto, Nicholas B. Brookes, Lucio Braicovich, Ke-Jin Zhou, Giacomo Ghiringhelli, Marco Moretti Sala

摘要:

基于$_2$ $_{3+δ}$(BCO)的合成,利用多晶样品上Cu $L_3$ X射线吸收(XAS)和Cu $d_{3z^2-r^2}$边的共振非弹性X射线散射(RIXS)研究了其电子结构.我们表明,BCO的XAS配置文件的特点是由两个峰相关的不等价的铜网站,其RIXS响应功能的一个单一的,尖锐的峰相关的晶场激发。我们认为,这些观察结果只是部分兼容先前提出的晶体结构的BCO。基于我们的光谱结果和先前发表的粉末衍射测量,我们提出了一种晶体结构,其特征在于两个不等价的Cu网站位于交替的平面沿$c$轴:名义上三价Cu(1)属于非常短的Cu-O链,和二价Cu(2)在缺氧的CuO $_ {1.5}$平面。我们还分析了RIXS谱的低能区域,以估计BCO中磁相互作用的大小,并发现面内最近邻超交换超过120 meV,与其他层状铜氧化物类似。虽然这些结果不支持纯$d_{3z^2-r^2}$基态的情况下,他们暗示在一个显着偏离常见的准二维电子结构的超导铜氧化物的纯$d_{x^2-y^2}$对称性。

英文摘要:

Motivated by the recent synthesis of Ba$_2$CuO$_{3+δ}$ (BCO), a high temperature superconducting cuprate with putative $d_{3z^2-r^2}$ ground state symmetry, we investigated its electronic structure by means of Cu $L_3$ x-ray absorption (XAS) and resonant inelastic x-ray scattering (RIXS) at the Cu $L_3$ edge on a polycrystalline sample. We show that the XAS profile of BCO is characterised by two peaks associated to inequivalent Cu sites, and that its RIXS response features a single, sharp peak associated to crystal-field excitations. We argue that these observations are only partially compatible with the previously proposed crystal structure of BCO. Based on our spectroscopic results and on previously published powder diffraction measurements, we propose a crystalline structure characterized by two inequivalent Cu sites located at alternated planes along the $c$ axis: nominally trivalent Cu(1) belonging to very short Cu-O chains, and divalent Cu(2) in the oxygen deficient CuO$_ {1.5}$ planes. We also analyze the low-energy region of the RIXS spectra to estimate the magnitude of the magnetic interactions in BCO and find that in-plane nearest neighbor superexchange exceeds 120~meV, similarly to that of other layered cuprates. Although these results do not support the pure $d_{3z^2-r^2}$ ground state scenario, they hint at a significant departure from the common quasi-2D electronic structure of superconducting cuprates of pure $d_{x^2-y^2}$ symmetry.

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