title: Ultrafast quenching of the exchange interaction in a Mott insulator.
abstract: We investigate how fast and how effective photocarrier excitation can modify the exchange interaction J_{ex} in the prototype Mott-Hubbard insulator. We demonstrate an ultrafast quenching of J_{ex} 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 J_{ex} emerges already within a few electron hopping times after the pulse, with a reduction that is comparable to the effect of chemical doping.
authors.affiliation: Max Planck Research Department for Structural Dynamics, University of Hamburg-CFEL, 22761 Hamburg, Germany.
authors.forename: J H
authors.initials: JH
authors.lastname: Mentink
authors.affiliation: Max Planck Research Department for Structural Dynamics, University of Hamburg-CFEL, 22761 Hamburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Eckstein