Using ultrashort optical pulses to couple ferroelectric and ferromagnetic order in an oxide heterostructure

Y. M. Sheu; S. A. Trugman; L. Yan; Q. X. Jia; A. J. Taylor; R. P. Prasankumar

doi:10.1038/ncomms6832

paper

Using ultrashort optical pulses to couple ferroelectric and ferromagnetic order in an oxide heterostructure

arXiv:1501.01753 · doi:10.1038/ncomms6832

Abstract

A new approach to all-optical detection and control of the coupling between electric and magnetic order on ultrafast timescales is achieved using time-resolved second harmonic generation (SHG) to study a ferroelectric (FE)/ferromagnet (FM) oxide heterostructure. We use femtosecond optical pulses to modify the spin alignment in a Ba $_{0.1}$ Sr $_{0.9}$ TiO $_{3}$ (BSTO)/La $_{0.7}$ Ca $_{0.3}$ MnO $_{3}$ (LCMO) heterostructure and selectively probe the ferroelectric response using SHG. In this heterostructure, the pump pulses photoexcite non-equilibrium quasiparticles in LCMO, which rapidly interact with phonons before undergoing spin-lattice relaxation on a timescale of tens of picoseconds. This reduces the spin-spin interactions in LCMO, applying stress on BSTO through magnetostriction. This then modifies the FE polarization through the piezoelectric effect, on a timescale much faster than laser-induced heat diffusion from LCMO to BSTO. We have thus demonstrated an ultrafast indirect magnetoelectric effect in a FE/FM heterostructure mediated through elastic coupling, with a timescale primarily governed by spin-lattice relaxation in the FM layer.

Using ultrashort optical pulses to couple ferroelectric and ferromagnetic order in an oxide heterostructure

Abstract

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