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Research Interests

The overarching goal of my research is the theoretical and computational study of strongly correlated electron systems, and the understanding of the complexity that emerges from these systems at the nanoscale. Within this theme, my research comprises classical systems, spin-fermion models and fully quantum mechanical models.

Part of my research has focused on the study of spin-fermion models for manganites, and the understanding of the colossal magneto-resistive (CMR) effect. We have found that the CMR is associated with short-distance correlations among polarons, above the spin ordering temperatures, resembling the charge ordered arrangement that appears at low-temperature. These polarons appear in states with nanoscale inhomogeneities that emerge from the competing interactions in the system.

The emerging nanoscale complexity found in manganites is found in other strongly correlated electron systems as well. I have used spin-fermion models to study the pseudo-gap phase of cuprate high temperature superconductors. We have developed a comprehensive theory of the pseudo-gap phase based on the competition between antiferromagnetism and superconductivity. We have extracted the local density of states measurements from this model and compared them with Scanning tunneling microscope (STM) measurements. We have also recently studied the Fermi surface obtained from our theory, and compared it with angle- resolved photo-emission spectroscopy measurements for cuprates. We have found that a state with nano-scale antiferromagnetic and superconducting clusters is in agreement with both STM and ARPES measurements.

Finally, for fully quantum systems, I have developed DMRG++, an implemen- tation of the DMRG algorithm that emphasizes generic programming using C++ templates. DMRG++ and our equivalent code for quantum Monte Carlo simula simulations, DCA++, is part of our effort to create computational kernels or solvers for condensed-matter models, such as the Hubbard model.

Invited papers, articles, book chapters and proceedings

•   Michael S Summers, Gonzalo Alvarez, Jeremy Meredith, Thomas A Maier and Thomas C Schulthess, DCA++: A case for science driven application development for leadership computing platforms , J. Phys.: Conf. Ser. 180 012077(2009)
• Elbio Dagotto, Seiji Yunoki, Cengiz Sen, Gonzalo Alvarez and Adriana Moreo, Recent developments in the theoretical study of phase separation in manganites and underdoped cuprates, J. Phys.: Condens. Matter 20 (2008) 434224
• G Alvarez, K A Al-Hassanieh, F Popescu, C Sen, A Moreo, and E Dagotto, Study of strongly correlated electrons in nanoscopic and bulk forms: some recent results, J. Phys.: Condens. Matter 19 (2007) 125213.
• Gonzalo Alvarez, Adriana Moreo, Elbio Dagotto, Complexity in high-temperature superconductors, Fizik a Nizkikh Temperatur, 2006, v. 32, No. 4, p. 290.
• Gonzalo Alvarez, Adriana Moreo, Elbio Dagotto, Complexity in transition metal oxides, Proc. SPIE Vol. 5932, p. 49-63 (2005)
• Article in Physics World Magazine of the IOP (December 2004): [Superconductors go large]
• Proceedings of the International Conference on Magnetism, ICM, Rome 2003. G. Alvarez and E. Dagotto, "Clustered States as a New Paradigm of Condensed Matter Physics", cond-mat/0305628. In Journal of Magnetism and Magnetic Materials (Elsevier) 272-276, 15 (2004)
• Contribution to Chapter 7, Monte Carlo simulations and Application to Manganite Models of Nanoscale Phase Separation and Colossal Magnetoresistance by E. Dagotto. Springer-Verlag Berlin Heidelberg 2003.

Invited Talks at Conferences, Seminars and Workshops

•   Invited talk at the Strongly Correlated Electron Workshop on Oxide Heterostructures, June 17-18, 2008.
• Poster Presentation (with T. Schulthess) at the NCCS User Meeting, Oak Ridge, TN, March 26-27, 2007.
• Invited talk at the 2006 workshop "Competing interactions and colossal responses in transition metal oxides", July 16-22, Telluride, Co. Program
• Invited talk at the 2006 March Meeting of the American Physical Society (APS) held in Baltimore, MD. [abstract at APS website]
• Invited talk at the University of Tennessee, Knoxville. South College Seminar Series, February 27, 2006.
• Invited talk at the Fall Creek Falls Conference Oct. 16-18, 2005.
• Invited talk at the Strongly correlated electrons miniprogram at the KITP of UCSB. Santa Barbara, CA, July 2005. [external link].
• Invited talk at the Second Coordination Meeting on Predictive Capabilities for Strongly Correlated Systems Nov 19-21, 2004. on Polynomial Expansion Method for Fermion Systems coupled to classical fields. More Info
• Invited Presentation at Condensed Matter II Class, Florida State University, March 23rd, 2004.
  
• Invited Talk,  Relevance of Clustered States in Diluted Magnetic Semiconductors and Other Materials, University of Maryland, March 3rd, 2004. Schedule
• Invited Speaker, Seminar, Rutgers University, February 26th, 2004. Schedule
• Invited Speaker, Workshop. UF/FSU Workshop on Condensed Matter, Gainesville, FL, April 26, 2003. Program (in PDF)

Conferences and Workshops Attended and Contributed Talks.

•  March Meeting of the American Physical Society (APS), 2008, New Orleans, LA. Abstract: B10.00004: Possible Explanation of the Fermi Arcs in Cuprates, based on a clustered superconducting state above Tc.
• IBM Blue Gene Workshop, October 31, 2007, American Museum of Science and Energy in Oak Ridge.
• CNMS User Meeting 2006
• March Meeting of the American Physical Society (APS) 2005, Los Angeles, CA. U43.00010: Superconducting Clusters and Colossal Effects in Underdoped Cuprates
• Monte Carlo Methods for Classical and Quantum Spin Systems and Beyond, organized by " The Nanomaterials Theory Institute of the Center for Nanophase Materials Sciences at Oak Ridge National Laboratory". Oak Ridge, TN. August 4-8, 2003. Overview
• March Meeting 2003, Austin, TX.
  Section S24.004. Dynamical and transport properties of a spin-fermion model for Diluted Magnetic Semiconductors. Abstract.
• March Meeting 2002, Indianapolis, IN.,
  Section L19.003 Monte Carlo Study of Dilute Magnetic Semiconductors. Abstract