Ultrafast frustration breaking and magnetophononic driving of singlet excitations in a quantum magnet

Abstract

Ultrafast laser probing has revolutionized the study of quantum materials. Quantum magnets realize some of the most complex and entangled many-body states in condensed matter. Here, the authors unify ultrafast physics and quantum magnetism by pump-probe experiments on the frustrated magnet SrCu${}_{2}$(BO${}_{3}$)${}_{2}$, using terahertz light pulses to create coherent driving of the lattice phonons, which in turn creates a special singlet spin excitation. Their phonon-based method introduces a universal mechanism for controlling nonequilibrium quantum many-body physics on ultrafast timescales.