Abnormal $phase$ flip in coherent phonon oscillations of Ca${}_2$RuO${}_4$

Min-Cheol Lee, Choong H. Kim, Inho Kwak +9

We employ an optical pump-probe technique to study coherent phonon oscillations in Ca${}_2$RuO${}_4$. We find that oscillation-amplitude of an $A_g$ symmetric phonon mode is strongly s…