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材料学院2018学术报告一:StrainControlandSizeScalingEffectinMultiferroi   2018/1/3 15:03:47   浏览次数:189

  

 

 

报告主题:Strain Control and Size Scaling Effect in Multiferroic BiFeO3 Thin Films —Towards Low-Power Nanoelectronics and Spintronics

 

报告嘉宾:陈祖煌,博士

报告时间:2018年01月08日(周一)上午10:00-11:00

报告地点:材料学院B2-537(西丽校区)

 

 

报告人简介:

陈祖煌博士,2006年本科毕业于厦门大学材料系,2008年硕士毕业于浙江大学材料系,2012年于新加坡南洋理工大学材料科学与工程系获博士学位。2013年起先后在美国伊利诺伊大学香槟分校(UIUC)材料系、加州大学伯克利分校材料系和劳伦斯伯克利国家实验室材料部从事博士后研究,合作导师为R. Ramesh院士和Lane Martin教授。近十年来一直从事铁电和多铁等复杂功能氧化物薄膜、异质结和纳米结构的外延生长,及其多场下铁电、压电、光电和磁电等性能调控及相关物理机制研究,并致力于其在低功耗非挥发性存储器等电子元器件的应用。目前已经在Phys. Rev. Lett., PNAS, ACS Nano, Adv. Mater., Nano Letters., Adv. Funct. Mater.,等国际期刊上发表论文49篇。对于铁性外延薄膜的晶格对称性,铁性材料畴工程的控制和畴壁功能性,铁电薄膜面内极化的反转控制和测量,氧化物自组装纳米结构制备及其在超材料的应用等方面的研究做出了原创性贡献。被发表在Nature, Nature Nano., Nature Mater., Nature Phys.,Rev. Mod. Phys.和Nature Rev. Mater.,等多种国际期刊引用>1000次,H因子18。此外受邀为Nano Lett., Adv. Mater.等十多种国际期刊审稿,并担任斯坦福同步辐射光源 (SLAC) User Proposal评审人。

 

 

报告主题:

Multiferroic materials such as BiFeO3 have motivated a generation of scientists to dream of the novel functionalities and exciting applications, such as using electric-field control of magnetism for low-power spintronics and nanoelectronics. But, despite tireless efforts in the community to understand, manipulate, and, ultimately, utilize the innate properties of what has become the most widely studied multiferroic today, countless questions as to the fundamental nature of BiFeO3 remain. In turn, few materials can offer the paradigmatic combination of vast potential and excitement with a frustrating lack of utility and overall complexity that BiFeO3 can provide. Ultimately, such complex materials as BiFeO3 remain ensconced in our minds because they challenge our ability to exert control on materials as we desire.

In this talk, I will address two different aspects associated with controlling magnetic ordering in this complex material. First, I will introduce our studies on strain control of antiferromagnetic spin structure and magnetic anisotropy in BiFeO3 thin films and heterostructures. Here, X-ray linear dichroism and first-principles calculations will reveal that epitaxial strain can be used to continuously tune the antiferromagnetic spin-axis orientation in BiFeO3 films across a wide angular space and thus control the magnetic anisotropy of an exchange-coupled ferromagnetic layer. We highlight an unexpected deviation of the classical perpendicular relationship between the antiferromagnetic axis and the polarization vector. First-principles calculations suggest that the magnetic anisotropy in is tunable with strain by leveraging the interplay between Dzyaloshinsky-Moriya interactions and single-ion-anisotropy. Second, I will present our recent studies on size-scaling effects on the antiferromagnetic and ferroelectric orderings in BiFeO3 filmsand its consequent effect on exchange coupling in Co0.9Fe0.1/BiFeO3 heterostructures. In turn, this understanding will enable the control of magnetism using electric field for nonvolatile memory devices with low-power energy consumption. I will show that we are able to switch the ferroelectric polarization by < 0.5 V in 20 nm BiFeO3. We find that ferroelectric and antiferromagnetic ordering is very robust down to at least 1 nm. Early observations on ultrathin version of BiFeO3films (<=2 nm) reveal that interfacial oxygen octahedral rotation coupling could stabilize new metastable single-domain tetragonal phase in BiFeO3 with exotic antiferromagnetic domain structure and robust ferroelectric ordering. These studies pave the way for realization of nanoelectric and spintronic devices with ultralow-energy consumption (~1 aJ/op, Note that Attojoule device is 6 orders of magnitude lower than today’s devices.) by using multiferroic BiFeO3.

 

 

欢迎感兴趣的师生前来参加!

材料学院

2018年01月02日

 
 
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