Two-Dimensional Spin-Peierls State With a Multimode Lattice Distortion (Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties)

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The effects of electron-electron (e-e) interactions on the two-dimensional (2D) Peierls state are discussed using the 2D Peierls-Hubbard model (2D PHM) in the limit of U≫t_0, where U is the on-site e-e interaction parameter between up and down spin electrons and t_0 is the electron transfer integral between nearest neighbor sites. In this limit, the 2D PHM can be mapped onto the 2D spin-Peierls model (2D SPM) in which the effect of the lattice distortion is taken into account in the spin exchange interaction of the 2D Heisenberg model. As was demonstrated in a previous paper [J. Phys. Soc. Jpn. 69 (2000) 1769], the ground state of the 2D electron-lattice (e-1) system (the 2D 1/2-filled SSH model) is the so-called multimode Peierls state where the lattice distortion involves Fourier components with the nesting wave vector Q=(π/a,π/a), a being the lattice constant, and with those paralell to it. Using the exact diagonalization technique it is shown that the spin-Peierls transition with a mutlimode lattice distortion can occur in the 2D spin-lattice system similarly as in the 2D e-1 system.
社団法人日本物理学会の論文
2006-03-15