[16p-S4_201-1~12] 10.2 Fundamental and exploratory device technologies for spin

3:00 PM - 3:15 PM JST(6:00 AM - 6:15 AM UTC)English Presentation

[16p-S4_201-5] Controlling spintronic terahertz emission behaviors under in-plane electric polarization in artificial multiferroic structure

〇Shunsuke Mori^1,2, Yuta Sasaki², Woonjae Won², Yukiko K. Takahashi^2,3, Ken-ichi Uchida^1,2 (1.UTokyo, 2.NIMS, 3.Tohoku Univ.)

Keywords:

Spintronic THz emitter,Magnetic anisotropy,Ferroelectricity

The spintronic THz emitter, driven by a photoinduced spin current in a non-magnetic heavy metal (NM)/ferromagnetic metal (FM) bilayer structure, is attracting attention for various analytical applications. More recently, an artificial multiferroic system, consisting of a NM/FM bilayer formed on a ferroelectric (FE) substrates, has been also studied to actively control spintronic THz emission properties via an external electric field. A Pt/Ni-Fe bilayer on a FE substrate is one of the representative artificial multiferroic structures that exhibit tuning of spintronic THz emission due to piezoelectric effects. Induced piezoelectric strain modulates in-plane magnetic anisotropy in Ni-Fe layer, which tunes magnetization and attributed THz emission depending on directions of strain. However, these configurations require large and static electric fields. On the other hand, tunability of THz intensity in NM/FM/FE with out-of-plane spontaneous polarization has been recently reported. Such control of spontaneous polarization effects is a promising way to realize bias-free control of spintronic THz emission in artificial multiferroic structures. In this study, we found that spintronic THz signals in a NM/FM/FE artificial multiferroic structure are affected by the in-plane spontaneous polarization of FE even in the absence of an external electric field. Investigations of THz time domain spectroscopy on Pt/Ni₈₁Fe₁₉/LN X-cut substrates verified that THz intensity was periodically tuned by rotating directions of ferroelectric polarization from the direction of an external magnetic field. Magnetic hysteresis curves ensured in-plane magnetic anisotropy depending on directions of ferroelectric polarization. Accordingly, spintronic THz emission is enhanced along the easy axis. These results open new strategies for bias-free tuning of spintronic THz emission.