title: Nanoscale thermal cloaking in graphene via chemical functionalization.
abstract: Macro-thermal cloaking is typically produced by coordinate transformations, but this method is unsuitable for nanostructures. We designed a graphene-based nanoscale thermal cloak using a novel mechanism of phonon localization. The nanocloak in graphene was produced via the chemical functionalization of hydrogen, methyl and hydroxyl using molecular dynamics simulations. The cloaking performance was quantified by the ratio of thermal cloaking (RTC). We found that the RTC correlated with the functionalization fraction and it has a local maximum at a certain width, since the heat flux reduction in the exterior and the protected region reversed if the width was excessive. The atomic mass of the functional group also correlated with the RTC. Our simulations determined that phonon localization occurred due to sp2-to-sp3 bonding transitions, which caused the heat flux to avoid the transition region. Finally, the extent of phonon localization was related to the cloaking performance.
authors.affiliation: Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, P. R. China. caoby@tsinghua.edu.cn.
authors.forename: Zhen-Qiang
authors.initials: ZQ
authors.lastname: Ye
authors.affiliation: Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, P. R. China. caoby@tsinghua.edu.cn.
authors.forename: Bing-Yang
authors.initials: BY
authors.lastname: Cao