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Complexity as a Result of Competing Orders in Correlated Materials. Adriana Moreo Dept. of Physics and ORNL University of Tennessee, Knoxville, TN, USA. Supported by NSF grants DMR-0443144 and 0454504. Outline. CMR manganites (short overview) High-Tc cuprates Phonons (new results)
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Dept. of Physics and ORNL
University of Tennessee, Knoxville,
Supportedby NSF grants DMR-0443144
Common theme emerging:
Clustered states and dramatic effects as a result of small perturbations (complexity)
Rich phase diagram, several states
competing. Common feature of many
Strongly Correlated Electronic systems.
Potential application in
First order or
Akahoshi et al.
Argyriou et al.,
PRL; De Teresa
Toy Model with disorder
Burgy et al., PRL87, 277202 (2001). See also Nagaosa et al.
WPhase Competition in the Presence of Quenched Disorder
MR ratios as large as 1000% at H=0.01.CMR effect due to inhomogeneous states
Field is small, but effective spin is large!
Elastic effects (see also
Bishop, Egami,…) are important for
this to occur in both D=2 and 3
(Burgy et al, PRL 92, 097202 (04)).
See also K. Yang, H. Ahn et al., …
FM up FM down Insulator Disorder
Ca2-x Nax Cu O2 Cl2
Hanaguri et al.
BiSCO (Hoffman et al.)
Switch to phenomenology
for underdoped region …
Large clusters and computational methods needed.New Trends: Inhomogeneities in cuprates. Are stripes universal?
Homes et al.,
J’A Spin-Fermion Model as aphenomenological model for HTSC
A.M. et al., PRL 84, 2690 (2000); PRL 88, 187001 (2002) (S classical)
Monte Carlo results for ``mean-field-like’’ model of mobile electrons coupled to classical AF (A.M. et al., PRL 88, 187001 (2002)) and SC order parameters (Alvarez et al., cond-mat/0401474). Two parameters: J and V.
AF+SC SC AF
Stripes become more localized
The stripes become more dynamic
Stripes are induced in a uniform ground state
Extended breathing mode
Phonons stabilize tiles and stripes
A.M. and J. Riera (in preparation)
Phonons stabilize stripes!
G. Alvarez (ORNL) C. Sen (FSU)
E. Dagotto (UT/ORNL) M. Mayr (Stuttgart)
T. Hotta (Tokai) S. Yunoki (Trieste)
J. Riera (Argentina) Y.Yildirim (UT)