1. “Strongly correlated electrons in bulk and nanoscopic systems” Theory of Condensed Matter Elbio Dagotto, Distinguished Professor, UT-ORNL

2. Organization (I)Complex transition metal oxides (high temperature superconductors, manganites, etc) (II) Oxides multilayers. (III) Transport in nanoscopic systems. UT Strongly Correlated Strongly CorrelatedElectrons UT Bulk (Mn,Cu oxides) Bulk (Mn,Cu oxides) UT Nano (Transport, Nano (Transport,Interfaces)

3. Publications Check http://sces.phys.utk.edu 2004-2008: 17 papers in Physical Review Letters; 28 in Physical Review B; 2 in Science; 1 in Physics World. Support provided by NSF and DOE. 4 students graduated during Summer 2007. Currently at BNL, LANL, UC, and Boston College. 5 new students arrived. 5 postdocs + many visitors. We will consider hiring new students. Ideal candidates should have the comprehensive exam approved, and at least Solid State I approved. Work is computationally intense; strong competition with other groups; definitely a full time job.

4. Strongly Correlated Electronic Materials (rich phase diagrams, nanoscale inhomogeneities, giant responses) (E.D., Science 309, 257 (2005)) NON-PERTURBATIVE METHODS “Strongly correlated electrons is the new frontier” (A. Cho, Science 314, 1072 (2006)) Risky but potentially rewarding business! Materials where Coulombic repulsion and strong e-ph couplings play a key role. Manganites

5. (I) Colossal Magneto Resistance (CMR) Resistivity of Mn-oxides changes by 10 orders of magnitude at low T Potential applications in read sensors, but critical temperatures must increase.

6. Resistance vs. temperature, Monte Carlo simulations. Shape very similar to CMR Experiments. Large magneto-resistance observed. Summary: CMR appears in a tiny cluster! We can easily ask “questions” to the computer. Similar to experimental physics. C. Sen, G. Alvarez, E.D., PRL 98, 127202 (2007).

7. Or igin of CMR? Short-range charge order; i.e. small regions of competing CO phase below a T*. Typical MC snapshot. Nanoscale structures are spontaneously formed (“self organization”). See also S. Yunoki et al., PRL 80, 845 (1998); A. Moreo et al., Science 283, 2034 (1999); ED et al, Phys. Rep. 344, 1 (2001); J. Burgy et al., PRL 87, 277202 (2001) and PRL 92, 097202 (2004).

8. High Temperature Superconductors High Temperature Superconductors Phase competition, as in manganites. Nanoscale inhomogeneities, as in manganites. Giant responses, as in manganites. T x Layered structure.

9. Underdoped high-Tc similar to Mn oxides? Patches of SC ? Non-interacting fermions + classical AF and SC order parameters; Alvarez et al., PRB 71, 014514 (2005); M. Mayr et al., PRB 73, 014509 (2006) Region of giant responses? Vortex liquid? (Ong) AF  e i  SC clean dirty True phase diagram of cuprates in clean limit? Main result: W T* T FMAf mixed

10. Recent STM results for BSCCO above Tc (Gomes et al., Nature 447, 569 (2007)) Optimal Tc=93K Region of SC clusters, as predicted by theory in 2005 80a x 80a AF

11. (II) Oxide interfaces and superlattices New playground in SCES. Many groups working on this subject (see E. D., Science 318, 1076 (2007))

12. Correlated electron multilayers: Applications of complex oxides? Oxide electronics? Ohtomo et al, Nature 419 (‘02) See also Mannhart, Triscone, Hwang, Tokura, Ramesh, Okamoto, … z LaTiO 3 SrTiO 3 LTOSTO

13. SMO/LMO/SMO/LMO … LaMnO3/CaMnO3 layers. Both AF insulating, but combination is FM metallic. Yunoki et al., PRB78, 024405 (2008); PRB76, 064532 (2007). Dong et al., Cond-mat/0810.1441. MC, DMRG, Poisson Eq.,…

14. (III) Effects of strong interactions in molecular conductors and QDs Interactions are important at low T: Kondo effect observed in molecules with net spin (peak in conductance) Nature 391, 156 (98); 417, 722 (02); 417, 725 (02); Science 280, 567 (98); 281, 540 (98).

15. Transport in SCES systems (t-DMRG, S. R. White and A. Feiguin 2004) One Dot Current vs. time Al-Hassanieh et al., PRB73,195304 (2006) Time unit ~ 10 fs (10^-15) if t=0.1 eV “1000” = 10 ps

16. Interferences in dots and molecules (G. Martins et al., PRL 96, 066802 (2006); PRL 94, 026804 (2005); K. Al-Hassanieh et al., PRL 95, 256807 (2005); Lanczos + embedding)

17. Time-dependent phenomena in SCES (in progress) Excitons in Mott insulators and polymers, relevant for solar energy. (Reboredo, Al-Hassanieh, Gonzalez, ED, PRL 2008) Breaking of a Mott insulator by strong bias (Al-Haasanieh, Dias, ED, …)

18. Summary Nanoscale self-organization and complex oxides: Solution of the CMR puzzle at hand. SC puddles in underdoped cuprates. Oxide multilayers: New phases? New functionalities? Quantum transport in strongly correlated systems: Another novel playground.