2010/12/16 by S. Bhattacharya, Bhattacharya, S., M. S. Ferreira +4
Biochemistry, Genetics and Molecular Biology · Materials Science · Physics and Astronomy · #Electron Spin Resonance Studies #FOS: Physical sciences #Magnetism in coordination complexes #Materials Science (cond-mat.mtrl-sci) #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Organic and Molecular Conductors Research #Strongly Correlated Electrons (cond-mat.str-el) #cond-mat.mes-hall #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.48550/arxiv.1012.3694
arxiv created 2010/12/16 · openalex publication_date 2010/12/16 · arxiv updated 2010/12/17 · openalex created_date 2024/04/10 · openalex updated_date 2026/07/28
We present a Monte Carlo study of the finite temperature properties of an extended Hubbard-Peierls model describing one dimensional π-conjugated polymers. The model incorporates electron-phonon and hyperfine interaction and it is solved at the mean field level for half filling. In particular we explore the model as a function of the strength of electron-electron and electron-phonon interactions. At low temperature the system presents a diamagnetic to antiferromagnetic transition as the electron-electron interaction strength increases. At the same time by increasing the electron-phonon coupling there is a transition from a homogeneous to a Peierls dimerized geometry. As expected such a Peierls dimerized phase disappears at finite temperature as a result of thermal vibrations. More intriguing is the interplay between the electron-phonon and the electron-electron interactions at finite temperature. In particular we demonstrate that for a certain region of the parameter space there is a spin-crossover, where the system transits from a low-spin to a high-spin state as the temperature increases. In close analogy to standard spin-crossover in divalent magnetic molecules such a transition is entropy driven. Finally we discuss the role played by the hyperfine interaction over the phase diagram.