8 research outputs found
Percolative nature of the transition from 60 K to 90 K phase in YBa2Cu3O6+d
We have measured the heat capacity of YBa2Cu3O6+d for 0.7<d<0.8 between 1.8
and 300K. It was found that doping dependences of specific heat jump and
temperature of heat capacity jump contradict to the assumption of spatially
homogeneous electronic density. The results suggest that the transition from
60K to 90K phase has a percolative nature and the structure of underdoped 60K
phase can be considered as array of superconducting nanoclusters embedded in
the insulating matrix.Comment: Submitted to proceedings of M2S-IX 2009, Tokyo (Physica C
Superstripes and complexity in high-temperature superconductors
While for many years the lattice, electronic and magnetic complexity of
high-temperature superconductors (HTS) has been considered responsible for
hindering the search of the mechanism of HTS now the complexity of HTS is
proposed to be essential for the quantum mechanism raising the superconducting
critical temperature. The complexity is shown by the lattice heterogeneous
architecture: a) heterostructures at atomic limit; b) electronic heterogeneity:
multiple components in the normal phase; c) superconducting heterogeneity:
multiple superconducting gaps in different points of the real space and of the
momentum space. The complex phase separation forms an unconventional granular
superconductor in a landscape of nanoscale superconducting striped droplets
which is called the "superstripes" scenario. The interplay and competition
between magnetic orbital charge and lattice fluctuations seems to be essential
for the quantum mechanism that suppresses thermal decoherence effects at an
optimum inhomogeneity.Comment: 20 pages, 3 figures; J. Supercon. Nov. Mag. 201