The quantum states in the strongly correlated electron systems

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My research activities consist of investigating the electronic properties of the high-temperature superconductors, and of studying the Heisenberg spin (magnetic) systems. High-temperature superconductors are poor electric conductors at high enough temperatures, but become superconductors (that conduct electricity without energy loss) when they are cooled below a certain critical temperature, which depends on the chemical composition of the material. For these materials, I am interested in understanding the differences that exist between their electronic properties and those of ordinary metals like copper for example. This understanding would likely help us understand the interplay between superconductivity and antiferromagnetism, which constitutes currently one of the most difficult issues of condensed matter physics. I use the concept of rotating magnetism in my research work on the high-temperature superconductors. More precisely, rotating antiferromagnetism is utilized in the modeling of the pseudogap behavior in these materials. For the spin systems, I look for the possible spin states that are realized in the so-called antiferromagnetic Heisenberg ladders and layers. These states are nontrivial arrangements of the spin average orientations. The spin arrangements depend on the number of legs in the ladders, or the number of layers in the Heisenberg coupled layers, and on the spin-spin coupling constant. Also, I am interested in the state that results form the interaction of the magnetic and lattice degrees of freedom. In the one-dimensional spin systems, this interaction leads to the spin-Peierls instability of the crystal lattice. A dimerization of the lattice parameter and the spin coupling constant results form this instability.