Authors: M Saarela F V Kusmartsev
Publish Date: 2015/01/10
Volume: 28, Issue: 4, Pages: 1337-1341
Abstract
We show that negatively charged dopant ions in holedoped layered highTc superconductors induce at low doping bound clusters of four holes in CuO layers This phenomenon requires double degeneracy of the hole band provided by the antiJahnTeller effect where dopant ions push apical oxygen ions into their symmetry positions and release holes from Copper atoms Experimentally that is seen as nanoscale inhomogeneity in the pseudogap region The broad pseudogap transition contains two separate transitions We connect the higher temperature transition to unbinding of clustered holes out of the spinsinglet state in the CuO plane The lower temperature transition removes directional stripy order of these dipolar clusters and the bosonic spinzero band disappears We report results on energetics of the cluster formation and fit the density parameter r s and dielectric constant to Hall measurements Our model leads to the quantum critical point at doping 02 where bound clusters disappear at zero temperature
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