Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session T60: Light-matter Interaction in Ferroelectrics and MultiferroicsFocus Recordings Available
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Sponsoring Units: DMP Chair: John Mangeri, Luxemburg Institute of Science and Technology Room: Hyatt Regency Hotel -DuSable C |
Thursday, March 17, 2022 11:30AM - 12:06PM |
T60.00001: Nonreciprocal optical responses of multiferroics Invited Speaker: Youtarou Takahash Multiferroics exhibit the strong magnetoelectric coupling, giving rise to the many intriguing phenomena. One such example is the optical response characterized by the nonreciprocity, in which the electric and magnetic dipole transitions interfere through the dynamical magnetoelectric coupling. Here, we focus on the optical response of the electromagnon, which is the magnon endowed with the electric activity, with strong dynamical magnetoelectric coupling. The spin orders which break the space-inversion symmetry induce the many nonreciprocal optical effects, which are especially enhanced on the electromagnon resonance, in the terahertz region. For example, the magnetically-induced chirality causes the large natural optical activity and magnetochiral effect. The magnetically-induced polarity, on the other hand, causes the directional dichroism and gyrotropic birefringence. We demonstrate these four distinct nonreciprocal optical effects on the spin-spiral magnets by using the time-domain terahertz polarimetry. |
Thursday, March 17, 2022 12:06PM - 12:18PM |
T60.00002: Optically Induced Picosecond Timescale Oxygen Octahedral Rotations in Multiferroic BiFeO3 Thin Films Deepankar Sri Gyan, Ni Li, Hyeonjun Lee, Youngjun Ahn, Eric C Landahl, Jerome Carnis, Jun Young Lee, Tae Yeon Kim, Sanjith Unithrattil, Ji Young Jo, Sae Hwan Chun, Sunam Kim, Sang-Yeon Park, Intae Eom, Carolina Adamo, Darrell G Schlom, Haidan Wen, Stephane Labat, Paul G Evans Structural effects originating from above bandgap optical excitation provide a route for ultrafast control of ferroelectricity and magnetism in multiferroic materials. The electrical and magnetic properties of multiferroic BiFeO3 depend on structural distortions arising from the rotations and tilts of FeO6 octahedra. We report an x-ray free-electron laser diffraction study designed to probe the dynamics of oxygen octahedral rotation (OOR) in a 35 nm BiFeO3 film epitaxially deposited on a (001) SrTiO3 substrate following a 3.1 eV optical pump pulse. The diffraction measurement recorded the time dependence of the reciprocal space location and intensities of half-integer reflections (0.5 0.5 2.5) and (0.5 1.5 2.5). Both reflections shifted to a lower out-of-plane wavevector following the optical excitation indicating that there is a transient photoinduced lattice expansion. The intensity of the (0.5 0.5 2.5) reflection depends on the in-plane OOR angles, providing a straightforward way to determine the tilt angle. The intensities of (0.5 1.5 2.5) reflections depend on both in-plane and out-of-plane OOR angles. A model for the dependence of the intensity on the in-plane and out-of-plane OOR angles was used to interpret the diffraction results. |
Thursday, March 17, 2022 12:18PM - 12:30PM |
T60.00003: Optically Induced Picosecond Lattice Compression in the Dielectric Component of a Strongly Coupled Ferroelectric/Dielectric Superlattice Deepankar Sri Gyan, Hyeonjun Lee, Youngjun Ahn, Jerome Carnis, Tae Yeon Kim, Sanjith Unithrattil, Jun Young Lee, Sae Hwan Chun, Sunam Kim, Intae Eom, Minseok Kim, Sang-Youn Park, Kyung Sook Kim, Ho Nyung Lee, Ji Young Jo, Paul G Evans A time-resolved x-ray free-electron laser diffraction study indicates that optical excitation of a strongly coupled 2(BaTiO3)/4(CaTiO3) (BT/CT) superlattice (SL) results in a transient overall photoinduced lattice expansion of the SL. There are two origins of the photoinduced distortion: a depolarization screening-driven structural change and an acoustic pulse launched from the bottom electrode on which the SL film was deposited. The acoustic pulse propagates through the film with a longitudinal sound velocity of 6 km/s, reflects from the surface, and propagates into the substrate. The depolarization screening-induced strain persists for a longer time. The intensities of the SL Bragg and satellite reflections were analyzed to determine the photoinduced strain in each component of the SL. The analysis showed the depolarization field screening led to an expansion of 0.04% in BT layers and a contraction of 0.01% in CT layers. The smaller magnitude of compression in CT layers can arise from the contribution of octahedral rotation patterns at BT/CT interfaces to the polarization of the CT layers. The photoinduced lattice compression and corresponding polarization reduction in CT points to a possibility of attaining metastable polarization configurations in strongly coupled SLs. |
Thursday, March 17, 2022 12:30PM - 12:42PM |
T60.00004: Evolution of phase domains in relaxor ferroelectric Pb(Mg1/3Nb2/3)O3 Hao Zheng, Dina Sheyfer, Bixia Wang, Ye Zuo-Guang, Matthew J Krogstad, Eric R Dufresne, Stephan Rosenkranz, Daniel Phelan, Carol Thompson, Hoydoo You, Gregory B Stephenson, Yue Cao Pb(Mg1/3Nb2/3)O3 or PMN is a relaxor perovskite that exhibits a giant dielectric response to the electric field over a broad temperature range with a frequency-dependent peak in dielectric permittivity. Such behavior, despite the intense debate of its origin, is believed to be strongly correlated to the phase domains, whose dynamics can be probed as the material is under external electrical stimuli. In this talk, we will present our recent study of wide-angle x-ray photon coherent spectroscopy (XPCS) on a PMN bulk crystal at the Advanced Photon Source. Using oscillating electric fields as the external stimuli, we observed strong responses of speckle patterns along different directions near the (0 0 2) Bragg peak. The two-time correlation displayed a periodic pattern with detailed structures and phase shifts, which will be explained by a phenomenological model. The speckle analysis in this work will provide a new dynamical view of the coupling between phase domains and electric fields in this material. |
Thursday, March 17, 2022 12:42PM - 12:54PM |
T60.00005: Magneto-optical properties of multifunctional BaTiO3-BiFeO3 films and nano-rod arrays Nicholas W Smith, Rathsara R Herath Mudiyanselage, Brenden A Magill, Giti A Khodaparast, Jade Holleman, Stephen McGill, Min Gyu Kang, Shashank Priya, Christopher J Stanton In this work, we focused on probing optical properties of BaTiO3-BiFeO3 films and nano-rod arrays, by employing transient reflectivity and time resolved magneto-optical Kerr effect. We perfomed these measurements via pump/probe optical techniques in high external magnetic fields (up to 10 T). The pump laser was fixed at 400 nm (1 KHz repetition rate), which allowed us to generate Coherent Longitudinal Acoustic Phonons (CLAPs) within the samples, and we used 800 nm pulses as the probe beam. We obserevd strong sensitivity of CLAPs to the external magnetic fields, and we also observed coherent oscillations with frequencies, close to the predicted magnon frequencies. The ability to generate strain via ultrafast optics offers the intriguing possibility of dynamically manipulating the strain in a given sample with ultrashort optical pulses, and opens the possibility of creating a new class of devices, on the basis our less explored multiferroics, where the strain can be manipulated in time to control the properties and operation of a device. |
Thursday, March 17, 2022 12:54PM - 1:06PM |
T60.00006: Photo-induced electric polirization in hybrid improper ferroelectrics Lingyuan Gao, Charles Paillard, Laurent Bellaiche Hybrid improper ferroelectrics form a class of materials for which the electric polarization is induced by two octahedral tilting modes, that are in-phase and antiphase tiltings. Interestingly, in conventional ferroelectrics, light has the tendency to suppress electrical polarization while enhancing tiltings. One may thus wonder what is the effect of light on electric polarization in hybrid improper ferroelectrics. Here, we use density functional theory and a novel light-matter ab-initio scheme [Physical Review Letters 123, 087601 (2019)] to address this question. Our study demonstrates that light can be a useful tool to drive and control polarization in original ferroelectric devices. |
Thursday, March 17, 2022 1:06PM - 1:18PM |
T60.00007: Nonreciprocal directional dichroism at telecom wavelengths Kiman Park, Michael O Yokosuk, Mateusz M Goryca, Junjie Yang, Scott A Crooker, Sang-Wook Cheong, Kristjan Haule, David Vanderbilt, Heung-Sik Kim, Janice Musfeldt Magnetoelectrics with ultra-low symmetry and spin-orbit coupling are well known to display a number of remarkable properties including nonreciprocal directional dichroism. As a polar and chiral magnet, Ni3TeO6is predicted to host this effect in three fundamentally different configurations, although only two have been experimentally verified. Inspired by the opportunity to unravel structure-property relations related to such a unique light-matter interaction, we combined magneto-optical spectroscopy and first principles calculations to reveal nonreciprocity in the toroidal geometry and compared our findings with those measured in the chiral configurations. We find that formation of Ni2+ toroidal moments is responsible for the largest effects near 1.1 eV - a tendency that is captured by our microscopic model and computational implementation. At the same time, we demonstrate deterministic control of nonreciprocal directional dichroism in Ni3TeO6 across the entire telecom wavelength range. This discovery will accelerate the development of photonics applications that take advantage of unusual symmetry characteristics. |
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