Using ultrashort optical pulses to control magnetoelectric materials

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(a) Schematic diagram of the interplay between the lattice, the magnetization M, and the ferroelectric polarization P at different times. (b) Time-­‐and-­‐polarization dependent second harmonic generation signal, indicating the photoinduced changes in ferroelectric order.

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Materials in which magnetic and electric order coexist have great potential for novel magnetoelectric devices, including applications in data storage, photovoltaics, and magnetic sensing. However, such materials are scarcely found in nature. Researchers at the Center for Integrated Nanotechnologies (CINT) aim to unravel key microscopic mechanisms that could advance a more abundant alternative—the engineering of artificial multiferroic composites at useful temperatures. The team successfully demonstrated a new approach to detect and control the coupling between electric and magnetic order on ultrafast timescales. The work reveals the dynamic properties of multiferroics, a rarely explored aspect that affects their potential applications. Nature Communications published the findings.

The team used femtosecond optical pulses to explore and optically manipulate the coupling between ferroelectric (FE) and ferromagnetic (FM) order in an oxide heterostructure for the first time. They discovered that the timescale dominating the magnetoelectric response is governed by demagnetization of the ferromagnetic layer through spin–lattice relaxation. Optically perturbing magnetic order in the ferromagnetic layer imposes lateral stress on the ferroelectric layer through magnetostriction, modifying ferroelectric order within tens of picoseconds. This finding demonstrates that femtosecond optical pulses can provide insight into the microscopic mechanisms underlying magnetoelectric coupling in complex oxide heterostructures and to manipulate the magnetoelectric response in these systems on ultrafast timescales.

Reference: “Using Ultrashort Optical Pulses to Couple Ferroelectric and Ferromagnetic Order in an Oxide Heterostructure,” Nature Communications 5, 5832 (2014); doi: 10.1038/ncomms6832. Authors include Yu-Miin Sheu (formerly with MPA-CINT), Stuart Trugman (Physics of Condensed Matter and Complex Systems, T-4), Li Yan (formerly with MPA-CINT), Quanxi Jia and Rohit Prasankumar (MPA-CINT), and Toni Taylor (Materials Physics and Applications, MPA-DO),

This work was performed at CINT, a DOE Office of Basic Energy Sciences user facility. The Laboratory’s Directed Research and Development (LDRD) program provided funding. The work supports the Lab’s Energy security mission area and the Materials for the Future science pillar. Multiferroics have potential applications, such as reducing the energy required to switch hard drives in computers. Technical contact: Rohit Prasankumar