Spectral Weight Distributions in Superconducting Condensates

by Tommy on 21/03/2017

This is something I’ve known for a long time, but now it’s official.


Coexistence of non-Fermi liquid and Fermi liquid self-energies at all dopings in cuprates, Sujay Ray and Tanmoy Das (18 March 2017)

Non-Fermi liquid (NFL) state represents an ensemble of incoherent quantum fluids arising from the coupling between electrons and massless (critical) excitations, and is separated by phase boundary from the quasiparticle behavior in the Fermi-liquid (FL) theory. Here we show that such sharp distinction breaks down in cuprates, and that both NFL and FL states coexists in different momentum (k) regions at all dopings. Their coexistence originates from the strong anisotropy in the many-body self-energy, arising from dispersive density-density fluctuations. The self-energy attains maxima (NFL-like) in the region where density degeneracy is optimum (antinodal region), while the nodal region remains FL-like at all dopings. We attribute the global NFL/FL behavior via the calculation of the resistivity-temperature exponent (n). Surprisingly, we find that the entire Brillouin zone becomes neither fully incoherent, NFL-like even at optimal doping with n = 1, nor fully FL-like even at overdoping (n = 2). As density degeneracy increases in different materials with increasing superconducting Tc, n decreases; providing a microscopic explanation to this intriguing relationship. All results, including coexistence of NFL- and FL-self-energies in the k-space, and their doping, materials dependencies are compared with available experimental data, followed by definite predictions for future studies.


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