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PACS numbers: 75.78.Jp, 71.10.Fd
Abstract:
We investigate how fast and how effective photocarrier excitation can modify the exchange interaction Jex in the prototype Mott-Hubbard insulator. We demonstrate an ultrafast quenching of Jex both by evaluating exchange integrals from a time-dependent response formalism and by explicitly simulating laser-induced spin precession in an antiferromagnet that is canted by an external magnetic field. In both cases, the electron dynamics is obtained from nonequilibrium dynamical mean-field theory. We find that the modified Jex emerges already within a few electron hopping times after the pulse, with a reduction that is comparable to the effect of chemical doping.
