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Research
Polarons
Recent studies have shed some more light on the nature of excitations
that make up the broad, gapped spectral feature through detailed studies
of Ca2-xNaxCuO2Cl2 as a
function of doping. Quasiparticles are coherent electron states that
form in metals, while “polarons” are the exact opposite—incoherent
excitations of electrons strongly coupled to a bath of lattice vibrations
and commonly found in insulators. This work suggests that the spectral
intensity near the Fermi level in the metallic copper-oxides evolves
from a polaron-like distribution of intensity in the pseudo-gaped insulators.
Further work shows that these polaronic excitations may be related
to a charge order in the pseudogap region of the phase diagram, seen
also by Scanning Tunneling Microscopy.
