US-Poland Cooperative Research on Effect of Strong Correlations and Disorder on Electron States and Phase Transitions in Vanadium Sesquioxides

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This U.S.-Poland Cooperative Research project on the Effect of Strong Correlations and Disorder on Electron States and Phase Transitions in Vanadium Sesquioxides is between Dr. J.M. Honig of Purdue University and Dr. Jozef Spalek of the University of Warsaw. The researchers plan a strongly interactive collaboration both in experiment and in theory for a thorough investigation of electron correlation effects and interaction-driven phase transitions in the (V1-xMx)2O3 system, with M = Cr, Ti, and cation vacancies and related systems. They will emphasize: (1) the proper preparation and characterization of single crystals grown by skull melting techniques; (2) measurements of heat capacity, magnetic susceptibility, and transport properties (with and without magnetic fields) in the cryogenic temperature range where lattice effects are negligible, to study their dependence on temperature, composition, and externally applied pressure; (3) the proper theoretical interpretation of the results in systems where both strong electron correlation and disorder effects determine the physical properties. The PI's involved in this project have had considerable experience in the area of materials preparation, physical measurements, and theoretical analysis, and have engaged in informal collaboration in the past. A principal result of the cooperation so far is the theoretical construction of an overall phase diagram for the (V1-xCrx)2O3 and V2(1-.)O3 systems, as well as the experimental discovery of a new boundary of V2(1-.)O3 terminating the antiferromagnetic metallic phase. They also plan as a follow-up to initiate a theoretical investigation of real space interactions involving hybrid pairing induced by Kondo-type interactions in various correlated electron systems. This research in condensed matter physics fulfills the program objectives of advancing science by enabling leading expert in the U.S. and Poland to combine complementary talents and pool research resources in areas of strong mutual interest and competence.