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
Clean limit result: Materials.
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
FM regionsConjectured CMR State in Manganites
A similar picture
will emerge in our
high Tc analysis.
High susceptibility to external magnetic fields:
rapid rotation of preformed nano-moments
(see also Cheong et al.)
Bi, tri, or
in clean limit.
quenched disorder(II) Similar Scenario in Cuprates?
LSCO Materials.(Yamada et al.)
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)
Phenomenological SC vs. AF competition Materials.
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.
T* Materials.Quenched disorder leads to clusters and T*, as in manganites.
centers, as in
Random orientation of the local SC phases Materials.
in glassy underdoped region
ManganitesCartoonish version of MC results
SC clusters Materials.
arches in FS
Quasiparticle dispersion in
20x20 cluster 60% AF and
40% d-wave SC.
Alvarez et al.
Spin Glass region (no SC)Theory vs Experiment
AF+SC SC AF
``non-SC glass’’ Materials.
“Colossal” Effects in underdoped regime?
(``Giant proximity effect’’ Decca et al. PRL, and Bozovic et al. submitted to Nature).
SC fields’’Giant proximity effect? (Alvarez et al., PRB71, 014514 (2005))
See Y. Yildirim and A.M. cond-mat/0503292Adiabatic Phonons
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)