title: Optical Diode Effect at Spin-Wave Excitations of the Room-Temperature Multiferroic BiFeO_{3}.
abstract: Multiferroics permit the magnetic control of the electric polarization and the electric control of the magnetization. These static magnetoelectric (ME) effects are of enormous interest: The ability to read and write a magnetic state current-free by an electric voltage would provide a huge technological advantage. Dynamic or optical ME effects are equally interesting, because they give rise to unidirectional light propagation as recently observed in low-temperature multiferroics. This phenomenon, if realized at room temperature, would allow the development of optical diodes which transmit unpolarized light in one, but not in the opposite, direction. Here, we report strong unidirectional transmission in the room-temperature multiferroic BiFeO_{3} over the gigahertz-terahertz frequency range. The supporting theory attributes the observed unidirectional transmission to the spin-current-driven dynamic ME effect. These findings are an important step toward the realization of optical diodes, supplemented by the ability to switch the transmission direction with a magnetic or electric field.
authors.affiliation: Department of Physics, Budapest University of Technology and Economics and MTA-BME Lendület Magneto-optical Spectroscopy Research Group, 1111 Budapest, Hungary.
authors.forename: I
authors.initials: I
authors.lastname: Kézsmárki
authors.affiliation: National Institute of Chemical Physics and Biophysics, 12618 Tallinn, Estonia.
authors.forename: U
authors.initials: U
authors.lastname: Nagel
authors.affiliation: Department of Physics, Budapest University of Technology and Economics and MTA-BME Lendület Magneto-optical Spectroscopy Research Group, 1111 Budapest, Hungary.
authors.forename: S
authors.initials: S
authors.lastname: Bordács
authors.affiliation: Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: R S
authors.initials: RS
authors.lastname: Fishman
authors.affiliation: Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: Hee Taek
authors.initials: HT
authors.lastname: Yi
authors.affiliation: Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: S-W
authors.initials: SW
authors.lastname: Cheong
authors.affiliation: National Institute of Chemical Physics and Biophysics, 12618 Tallinn, Estonia.
authors.forename: T
authors.initials: T
authors.lastname: Rõõm