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

这项关于强关联和无序对钒倍半氧化物电子态和相变的影响的美国-波兰合作研究项目是普渡大学的J.M.霍尼格博士和霍尼格博士共同完成的。华沙大学的Jozef Spalek说。研究人员计划在实验和理论上进行强交互合作，以彻底研究(V1-XMX)_2O_3系统中的电子关联效应和相互作用驱动的相变，具有M=铬、钛和阳离子空位及相关体系。他们将强调：(1)用头骨熔化技术生长的单晶的适当制备和表征；(2)在晶格效应可以忽略的低温温度范围内测量热容量、磁化率和输运性质(有和没有磁场)，研究它们对温度、成分和外加压力的依赖关系；(3)在强电子关联和无序效应共同决定物理性质的系统中，对结果进行了适当的理论解释。参与这个项目的PI在材料准备、物理测量和理论分析方面都有相当的经验，并在过去进行过非正式合作。到目前为止，合作的一个主要结果是从理论上构建了(V1-xCrx)_2O_3和V_2(1-.)O_3系统的总相图，以及实验上发现的终止反铁磁金属相的V2(1-.)O_3的新边界。作为后续行动，他们还计划启动一项关于各种相关电子系统中近藤型相互作用引起的杂化配对的真实空间相互作用的理论研究。凝聚态物理的这项研究通过使美国和波兰的顶尖专家能够将互补的人才结合在一起，并在相互感兴趣和能力很强的领域汇集研究资源，从而实现了推进科学的计划目标。

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.