Time-resolved quasiparticle dynamics of the itinerant antiferromagnet UPtGa5

planes: (1) G-typeantiferromagnetism or (2) A-type antiferromagnetism, thatis, spins are ferromagnetically aligned along each plane, butantiferromagneticallyalignedinadjacentplanes.Beingabletoelucidate the magnetic alignment of the spins in multilayeredcuprate superconductors in the coexistence phase is crucialin narrowing down the starting point for a pairing theory inhigh-temperature superconductivity. It is therefore importantto study the QP dynamics of pure SDW systems beforeproceedingtomorecomplexcoexistencephasesinthecupratesuperconductors. At present there have been no systematicmeasurements of the QP dynamics of the SDW phase,