Ultrafast Double Pulse All-Optical Reswitching of a Ferrimagnet

All-optical re-switching has been investigated in the half-metallic Heusler ferrimagnet Mn2Ru0.9Ga, where Mn atoms occupy two inequivalent sites XA-type structure. The effect of a second 200 fs 800 nm pump pulse that follows first pulse, when both are above threshold for switching, is studied as function t12, time between them. aims to identify physical mechanisms involved and determine minimum needed re-switching. trajectory switching process on plot sublattice angular momentum, S4a vs S4c, three stages; When t < 0.1 ps, moments rapidly disordered, but not destroyed, while conserving net momentum via optical spin-wave excitations. This leads transient parallel alignment residual spins quadrant. associated with majority then flips about 2 fully-reversed ferrimagnetic state established spin-lattice interaction, which allows provided t12 > 10 ps.