Physics of Transition Metal Oxides and Related Materials

该奖项支持以计算为重点的理论研究，包括巨磁阻材料、高温超导体和其他相关的过渡金属材料。研究的主要目的是：(1)金属相与绝缘相相互竞争，形成复杂的混相顺磁绝缘状态；这个巨大的磁电阻也产生于这种竞争的想法将被调查。(2)对锰酸盐模型中的电荷顺序进行分析，重点放在中间空穴密度的未探索区域，在该区域，最近的实验已经揭示了相关极化子物理。探讨该地区形成赝隙的可能性。(3)研究铜酸盐、锰酸盐和其他过渡金属氧化物在非均相状态下的物理共性。条纹和超导性将在铜氧化物中探索，使用先进的方法来寻找配对和模型，以相当好地再现已知的实验结果。这些大尺度结构似乎是铜酸盐和锰酸盐共同物理特性的一部分。(4)稀磁半导体，掺锰砷化镓半导体的模型将被研究。预计这些材料的电子性质将与锰氧化物中的混合相具有共同的特征。该奖项支持以计算为重点的理论研究，包括巨磁阻材料、高温超导体、钌酸盐和掺杂磁性半导体。巨磁阻材料在适度的磁场作用下，其电阻率发生了巨大的变化，与掺杂磁性半导体一样，在新兴的自旋电子学领域可能具有重要意义。这些具有强电子相关性的过渡金属材料可以表现出奇异的电子态，包括大规模结构或条纹相以及电子激发谱中赝隙的出现。在研究的一个重点中，pi将使用最先进的蒙特卡罗方法来调查这些现象是否具有共同的物理基础。pi还将研究用于自旋电子学应用的锰酸盐和材料的共同特征，并阐明Ca2-x Srx RuO4的复杂相图的物理起源，包括顺磁性，铁磁性和反铁磁性相

This award supports theoretical research with a computational emphasis, on colossal magneto resistance materials, high temperature superconductors, and other correlated transition metal materials. The research has several aims: (1) A complex mixed-phase paramagnetic-insulating state arises from the competition between metallic and insulating phases; the idea that this colossal magneto resistance also arises from this competition will be investigated. (2) Charge ordering in models for manganites will be analyzed with emphasis on the unexplored region of intermediate hole densities where correlated polaron physics has been revealed in recent experiments. The possibility of pseudogap formation in this region will be explored. (3) Physics common to the cuprates, manganates and other transition metal oxides in the inhomogeneous states will be examined. Stripes and superconductivity will be explored in the copper oxides using advanced methods to search for pairing and models that reproduce known experimental results reasonably well. These large-scale structures appear to be part of the common physics in cuprates and manganates. (4) Models for dilute magnetic semiconductors, Mn-doped GaAs semiconductors, will be studied. It is anticipated that the electronic properties of these materials will have features in common with those of the mixed-phases in the manganese oxides. %%%This award supports theoretical research with a computational emphasis, on colossal magneto resistance materials, high temperature superconductors, ruthenates and doped magnetic semiconductors. Colossal magneto resistance materials show an enormous change in resistivity with the application of modest magnetic fields and like the doped magnetic semiconductors, may be important in the emerging field of spintronics. These transition metal materials with strong electronic correlations can exhibit exotic electronic states, including large-scale structure or striped phases and the appearance of a pseudogap in the electronic excitation spectrum. In one thrust of the research, the PIs will use state of the art Monte-Carlo methods to investigate whether these phenomena share a common physical basis. The PIs will also investigate the common features of manganates and materials useful for spintronics applications, and elucidate the physical origin of the complex phase diagram of Ca2-x Srx RuO4 which includes paramagnetic, ferromagnetic, and antiferromagnetic phases.***