Volume 32 Issue 5 - July 17, 2020 PDF
Deterministic optical control of room temperature multiferroicity in BiFeO3 thin films
Yi-De Liou1、Yi-Chun Chen1,2Jan-Chi Yang1,2,*
1 Department of Physics, National Cheng Kung University, Tainan, 701, Taiwan
2 Center for Quantum Frontiers of Research & Technology (QFort), National Cheng Kung University, Tainan, 701, Taiwan
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【The 18th Y. Z. Hsu Scientific Paper Award】Special Issue

With the rapid development of information technology, the existing electronic and memory devices no longer satisfy the requirement of the high-speed processing of large amounts of information. The development of new functional materials for novel device designation is therefore highly-desired. Multiferroic materials are treated as one of the most promising candidates for next generation memory device and nanoelectronics due to their coexisted and coupled ferroic orderings. In this study, we successfully demonstrate the optical control of ferroelectric, ferromagnetic and antiferromagnetic orderings in multiferroic bismuth ferrite (BiFeO3) thin films at room temperature. Unlike conventional memory writing operation conducted via electric/magnetic fields, these ferroic orderings are spatially arranged to a very special pattern (Figure 1). The key mechanism for optical manipulation is the thermal gradient generated by continuous wave laser, which can establish observable stress field and radiating flexoelectric field in the illuminated area, resulting in accurate variation of crystalline phases and multiferroic domains.
In addition to the deterministic alteration of multiferroic bits via light manipulation, the non-contact writing strategy eliminates the need for additional electrode manufacturing process on the memory materials. While the crystalline phase of the mixed-phase bismuth ferrite film is altered, various physical quantities such as surface morphology, antiferromagnetic, ferromagnetic, piezoelectric, dielectric and electrical conductivity of the mixed-phase bismuth ferrite can be accurately controlled and memorized. Recently, we have further discovered that this optical manner can be performed down to femtosecond timescale, showing its high potential for the development of future optoelectronics and related applications.

Optical control of multiferroic orderings in mixed phase BiFeO3 thin films
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