Open AccessDesign of Single‐Molecule Multiferroics for Efficient Ultrahigh‐Density Nonvolatile Memories
Author(s) -
Yang Qing,
Zhong Tingting,
Tu Zhengyuan,
Zhu Lin,
Wu Menghao,
Zeng Xiao Cheng
Publication year - 2019
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.201801572
Subject(s) - multiferroics , materials science , condensed matter physics , ferroelectricity , paramagnetism , bilayer , magnetization , bistability , switching time , nanotechnology , magnetic field , optoelectronics , physics , chemistry , biochemistry , quantum mechanics , membrane , dielectric
It is known that an isolated single‐molecule magnet tends to become super‐paramagnetic even at an ultralow temperature of a few Kelvin due to the low spin switching barrier. Herein, single‐molecule ferroelectrics/multiferroics is proposed, as the ultimate size limit of memory, such that every molecule can store 1 bit data. The primary strategy is to identify polar molecules that possess bistable states, moderate switching barriers, and polarizations fixed along the vertical direction for high‐density perpendicular recording. First‐principles computation shows that several selected magnetic metal porphyrin molecules possess buckled structures with switchable vertical polarizations that are robust at ambient conditions. When intercalated within a bilayer of 2D materials such as bilayer MoS 2 or CrI 3 , the magnetization can alter the spin distribution or can be even switched by 180° upon ferroelectric switching, rendering efficient electric writing and magnetic reading. It is found that the upper limit of areal storage density can be enhanced by four orders of magnitude, from the previous super‐paramagnetic limit of ≈40 to ≈10 6 GB in. −2 , on the basis of the design of cross‐point multiferroic tunneling junction array and multiferroic hard drive.