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MA: Fachverband Magnetismus

MA 9: Cooperative phenomena: Spin structures and magnetic phase transitions

MA 9.5: Vortrag

Montag, 1. April 2019, 16:00–16:15, H53

Photo-induced excitation and its relaxation in the magnetic and polaronic microstructure of a manganite studied by Ehrenfest dynamics — •Sangeeta Rajpurohit¹, Michael ten Brink^1,2, and Peter Blöchl^1,2 — ¹Institute for Theoretical Physics, Technical University Clausthal, Germany — ²Institute for Theoretical Physics, Universität Göttingen, Germany

With several recent experimental observations of the long-lived excited states, manganites are seen as promising candidates for the future energy devices. The theoretical understanding of relaxation process in the strongly correlated manganites by investigating the interplay of the charge, spin and lattice degrees is of great interest. A microscopic model, extracted from the first-principles calculations, is proposed to analyse the electronic, atomic and magnetic microstructure of the manganites. The model is used within the framework of the Ehrenfest-like dynamics to study the evolution of the photo-excited system. The time-dependent Schrodinger equation is adopted for the evolution of the electron wave functions and spin degree of freedom while the atoms are treated classically. The relaxation timescale and pathway in the photo-excited Pr_0.5Ca_0.5MnO₃, notably, depend on the light-pulse intensity. In the weak intensity case, the electronic sub-system relaxes through an ultrafast lattice-assisted conical intersection process. The spin dynamics on the sub-picosecond timescale plays a crucial role, besides lattice dynamics, if the system is subjected to a high-intensity light pulse. Interestingly, a new long-lived excited-state, exhibiting phase-separation, emerges at an intermediate light-pulse intensity.