Coherent phonon control via electron-lattice interaction in ferromagnetic Co/Pt multilayers

Abstract

The manipulation of coherent phonons in condensed systems has attracted fundamental interest, particularly for its applications to future devices. We demonstrate that a coherent phonon in Co/Pt nano-multilayer can be quantitatively controlled via electron-lattice coupling, specifically by changing the multilayer repeat number. To that end, systematic measurement of the time-resolved reflectivity and magneto-optical Kerr effect in Co/Pt multilayers was performed. The coherent phonon frequency was observed to be shifted with the change of the multilayer repeat number. This shift could be clearly explained based on the two-temperature model. Detailed analysis indicated that the lattice heat capacity and electron-lattice coupling strength are linearly dependent on the repeat number of the periodic multilayer structures. Accessing the control of coherent phonons using nanostructures opens a new avenue for advanced phonon-engineering applications.

Ultrafast giant magnetic cooling effect in ferromagnetic Co/Pt multilayers

“…As T s is related to the magnetization, which is a magnetic ordering parameter, the lower T s indicates a higher degree of magnetization (or equivalently larger remagnetization). The fitting results (Table 1 ) indicate that G el increases in proportion to n , as previously reported for the case of 2TM under no external field 34 . The increased G el indicates an increase in the electron–lattice interaction, suggesting that the remagnetization converging to the equilibrium becomes faster.…”