IAP Seminar (Strain and electrical tunability of spin-excitations in multiferroic BiFeO3 observed by resonant inelastic X-ray scattering)
Date : August 30, 2024 15:00 ~ 17:00
Speaker : Taehun Kim (NSLS-II, Brookhaven National Laboratory)
Professor : Prof. Je Geun Park
Location : 56-521
Strain and electrical tunability of spin-excitations in multiferroic BiFeO3 observed by resonant inelastic X-ray scattering
National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
The room-temperature multiferroic BiFeO3 has been extensively studied in the last two decades, as
it possesses promising properties like magneto-electric and magneto-elastic coupling without the
need for cryo-cooling. Many studies focused on resolving the magnetic structure, the ferroelectric
polarization, and the photo-striction effect as a function of external stimuli like strain, electric or
magnetic field, and a laser pump. However, information on spin-excitations and exchange
interactions is not available, hindered by the lack of experimental techniques.
Here, we performed resonant inelastic X-ray scattering (RIXS) on BiFeO3 (bulk, thin films) and
investigated the spin-excitations as a function of epitaxial strain and electric field. The linear
dichroism in the magnon provides evidence of different magnetic structures depending on the strain,
which is supported by atomic multiplet calculations. The magnon dispersion as a function of strain
reveals the different ratios in exchange interactions along in-plane and out-of-plane directions, also
supported by first-principles calculations. The ferroelectric polarization switching via electric field
causes changes in magnon energy, linewidth, and dichroism, which are reversible and repeatable.
Our findings provide unambiguous evidence of both the strain and electrical tunability of spinexcitations in BiFeO3