Abstract-Polarization switching in ferroelectric thin film induced by a single-period terahertz pulse

Elena Mishina,  Kirill Grishunin, Vladislav Bilyk, Natalia Sherstyuk, 

https://www.cambridge.org/core/journals/mrs-advances/article/polarization-switching-in-ferroelectric-thin-film-induced-by-a-singleperiod-terahertz-pulse/91CA5CE74306D2C39DC594B0BE31C92E

We report here an experimental study of ultrafast response of the dielectric polarization in (Ba0.8Sr0.2)TiO3 thin films to a strong electric field of a nearly single-cycle THz pulse. The phenomenon of Second Harmonic Generation (SHG) is used as a probe of the polarization in the terahertz pump-optical probe experiment. SHG loops for THz pulses of different amplitudes were obtained. The SHG response is modelled assuming that the ferroelectric material is split into 180-degree domains. It is shown that intuitive model based on forced harmonic oscillator does not fully describe to the observed ultrafast ferroelectric response.

COPYRIGHT: © Materials Research Society 2018 

Abstract-Terahertz Magnon-Polaritons in TmFeO3

Rasing, A. V. Kimel, Kailing Zhang, Zuanming Jin, Shixun Cao, Wei Ren, Guo-Hong Ma, Rostislav Mikhaylovskiy

http://pubs.acs.org/doi/abs/10.1021/acsphotonics.7b01402?mi=aayia761&af=R&AllField=nano&target=default&targetTab=std

Magnon-polaritons are shown to play a dominant role in the propagation of terahertz (THz) waves through TmFeO3 orthoferrite, if the frequencies of the waves are in the vicinity of the quasi-antiferromagnetic spin resonance mode. Both time-domain THz transmission and emission spectroscopies reveal clear beatings between two modes with frequencies slightly above and slightly below this resonance, respectively. Rigorous modelling of the interaction between the spins of TmFeO3 and the THz light shows that the frequencies correspond to the upper and lower magnon-polariton branches. Our findings reveal the previously ignored importance of propagation effects and polaritons in such heavily debated areas as THz magnonics and THz spectroscopy of electromagnons. It also shows that future progress in these areas calls for an interdisciplinary approach at the interface between magnetism and photonics.