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arXiv · 2204.10284

Characterization of two electronic subsystems in cuprates through optical conductivity

C. M. N. Kumar·Ana Akrap·Chris C. Homes·Edoardo Martino·Benjamin Klebel-Knobloch·Wojciech Tabis·Osor S. Barišić·Denis K. Sunko·Neven Barišić
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Abstract

Understanding the physical properties of unconventional superconductors as well as of other correlated materials presents a formidable challenge. Their unusual evolution with doping, frequency, and temperature has frequently led to non-Fermi-liquid (non-FL) interpretations. Optical conductivity is a major challenge in this context. Here, the optical spectra of two archetypal cuprates, underdoped HgBa$_2$CuO$_{4+δ}$ and optimally-doped Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$, are interpreted based on the standard Fermi liquid (FL) paradigm. At both dopings, perfect frequency-temperature FL scaling is found to be modified by the presence of a second, gapped electronic subsystem. This non-FL component emerges as a well-defined mid-infrared spectral feature after the FL contribution -- determined independently by transport -- is subtracted. Temperature, frequency, and doping evolution of the MIR feature identify a gapped rather than dissipative response. In contrast, the dissipative response is found to be relevant for pnictides and ruthenates. Such an unbiased FL/non-FL separation is extended across the cuprate phase diagram, capturing all the key features of the normal state and providing a natural explanation why the superfluid density is attenuated on the overdoped side. Thus, we obtain a unified interpretation of optical responses and transport measurements in all analyzed physical regimes and all analyzed compounds.

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C. M. N. Kumar, Ana Akrap, Chris C. Homes, Edoardo Martino, Benjamin Klebel-Knobloch, Wojciech Tabis, Osor S. Barišić, Denis K. Sunko, Neven Barišić. 2023-07-12. Characterization of two electronic subsystems in cuprates through optical conductivity. https://doi.org/10.1103/physrevb.107.144515

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