1. Time-Resolved Optical Studies of Collective Modes in Colossal Magnetoresistive Materials
Yuhang Ren, Physics & Astronomy, Hunter College of the City University of New York
Our research program is to study the low-energy dynamics of collective modes, spin coherence, and electron-lattice coupling under nonequilibrium conditions in colossal magnetoresistive compounds. We have now studied the anomalous first-to-zero sound crossover in La0.67Sr0.33MnO3 and the spin wave dynamics in La0.67Ca0.33MnO3 using ultrafast time-resolved optical techniques. We explain our data by the possible presence of a random spatial distribution of charge-ordering clusters.
1. Lattice dynamics in doped manganite: La0.67Sr0.33MnO3
phonon echo x
two-color
2. Spin and magnetization dynamics in doped manganite: La0.67Ca0.33MnO3
Heff
laser beams M
Heff
Voigt-geometry differential magnetic Kerr data of a 60-nm LCMO film grown on a (110) NdGaO3