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Robust spin and charge excitations throughout the high-Tccuprate phase diagram from incipient Mottness
Physical Review B ( IF 3.7 ) Pub Date : 
M. Fidrysiak, J. Spałek

The generic phase diagram of lightly hole-doped high-Tc-cuprates hosts antiferromagnetic insulating phase with well-defined spin-wave excitations. Contrary to the weak-coupling prediction, these modes persist up to the overdoped metallic regime as intense and dispersive paramagnons. Here we report on our study of the low-energy magnetic and charge excitations within the extended Hubbard model at strong-coupling, using a modified 1/N expansion method with a variational state serving as the saddle point solution. Despite clear separation of magnetic and Hubbard-U energy scales, we find that incipient Mottness affects qualitatively dispersions and widths of magnetic modes throughout entire phase diagram. The obtained magnetic and charge dynamical structure factors agree semi-quantitatively with recent resonant X-ray and neutron scattering data for La2𝑥Sr𝑥CuO4 and (Bi,Pb)2(Sr,La)2CuO6+δ at all available doping levels. The weak-coupling random-phase-approximation fails already for underdoped samples, pointing to the non-trivial intertwining of distinct energy scales in cuprate superconductors. The existence of a discrete charge mode which splits off the electron-hole continuum is also predicted.

中文翻译:

从初始Mottness到整个高速率相图中的强大自旋和电荷激发

轻度掺杂高通量的通用相图ŤC-杯状具有明确定义的自旋波激励的反铁磁绝缘相。与弱耦合预测相反,这些模式一直持续到超掺杂金属态,即强和分散的顺磁子。在这里,我们使用改进的方法,报告了我们在强耦合时扩展的Hubbard模型内对低能磁激发和电荷激发的研究1个/ñ变状态作为鞍点解的扩展方法。尽管磁性和Hubbard明显分开,ü在能量尺度上,我们发现初始莫特性在整个相图中定性地影响磁模的色散和宽度。所获得的磁和电荷动力学结构因子与近期共振半定量一致X的射线和中子散射数据 大号一种2-𝑥小号[R𝑥CüØ4一世Pb2小号[R大号一种2CüØ6+δ在所有可用的掺杂水平上。对于掺杂不足的样品,弱耦合随机相位近似已经失效,这表明铜酸盐超导体中不同能级的非平凡交织。还预测了分离电子-空穴连续体的离散电荷模式的存在。
更新日期:2020-07-06
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