Ultimate-density memory via flat phonon bands in HfO2
일 시 : 2021년 10월 14일 목요일 10:30
연 사 : 이 준 희 교수 (울산과기대 에너지화학공학과)
장 소 : 온라인 진행 ( https://us02web.zoom.us/j/87466083060?pwd=cTNQMEpqdElWbi9oRnQrdXdMcFJXUT09)
HOST : 조 준 형 교수님
초 록
Since ferroelectricity is a collective phenomenon necessitating thousands of atoms’ simultaneous displacement, it’s been believed since it’s discovery in 1920 that at least finite-sized domains (10~100nm) are required to stabilize and switch the ferroelectric dipole moments. Here, we show that we can break the 100-years myth if we introduce flat-band theory in the history of ferroelectricity. As flat band has been known to induce intrinsic local states and to cause very unusual phenomena such as graphene superconductivity and electron lattices, we, for the first time, show that flat band in ferroelectricity induces intrinsic local dipoles of unit-cell scale of a few angstroms [1]. These intrinsic local dipoles are individually stable and switchable, now one does not need the formation of the conventional domains for the dipole switching. We can directly switch the unit-cellscale dipoles and finally pave a way to achieve ultimate-density ferroelectric devices.
[1] “Scale-free ferroelectricity induced by flat honon bands in HfO2”, Lee et al., Science 369, 1343 (2020)