Domain walls, topological defects that define the frontier between regions of different stacking ... more Domain walls, topological defects that define the frontier between regions of different stacking in multilayer graphene, have proved to host exciting physics. The ability of tuning these topological defects in-situ in an electronic transport experiment brings a wealth of possibilities in terms of fundamental understanding of domain walls as well as for electronic applications. Here, we demonstrate through a MEMS (microelectromechanical system) actuator and magnetoresistance measurements the effect of domain walls in multilayer graphene quantum Hall effect. Reversible and controlled uniaxial strain triggers these topological defects, manifested as new quantum Hall effect plateaus as well as a discrete and reversible modulation of the current across the device. Our findings are supported by theoretical calculations and constitute the first indication of the in-situ tuning of topological defects in multilayer graphene probed through electronic transport, opening the way to the use of reversible topological defects in electronic applications. a) PA and YH contributed equally to this work.
X iv :s ub m it/ 35 00 04 6 [ co nd -m at .m es -h al l] 2 4 D ec 2 02 0 Signature of multilayer ... more X iv :s ub m it/ 35 00 04 6 [ co nd -m at .m es -h al l] 2 4 D ec 2 02 0 Signature of multilayer graphene strain-controlled domain walls in quantum Hall effect Paul Anderson, a) Yifan Huang, a) Yuanjun Fan, Sara Qubbaj, Sinisa Coh, Qin Zhou, and Claudia Ojeda-Aristizabal Department of Physics and Astronomy, California State University Long Beach, Long Beach, California 90840, USA Department of Mechanical and Materials Engineering, University of Nebraska, Lincoln 68588-0526, Nebraska, USA Department of Mechanical Engineering and Materials Science and Engineering Program, University of California, Riverside, Riverside, CA, 92521 USA
Table of Contents List of Figures List of Tables Chapter 1 Introduction and background 1.1 Graphi... more Table of Contents List of Figures List of Tables Chapter 1 Introduction and background 1.1 Graphite and Graphene 1.2 Graphene-based composite 1.3 Synthesis, fabrication and analysis 1.4 Application Chapter 2 Synthesis, isolation, and characterization of multi-layer graphene membrane 2.1 Growth mechanism 2.2 Synthesizing graphene membrane 2.2.1 Experimental apparatus of CVD 2.2.2 Mass flow ratio calculation 2.3 Isolation of graphene membrane 2.3.1 Traditional chemical route 2.3.2 Improved electrochemical route 2.3.3 Suspending the membrane and tension adjustment 2.4 Characterization of suspended graphene membrane 2.4.1 Raman spectrum 2.4.2 Thickness and uniformity measured by optical transmissivity microscopy 2.4.3 Ultimate tensile strength measurement and calculation 2.4.4 Resistivity measurement and calculation vi Chapter 3 Synthesis of graphene-based composite membrane 3.1 The ultimate tensile strength (UTS) of membrane affected by types of interaction bonding and fabrication methods 3.2 Fabricate graphene-based composite membrane 3.2.1 The principle of spin coating 3.2.2 Polyethyleneimine (PEI) modified GO composite membrane by spin coating 3.3 Evaluation of the composite membrane 3.3.1 Thickness measurement by AFM 3.3.2 UTS and resistivity measurement and calculation Chapter 4 Results and discussion 4.1 Analysis of graphene membrane 4.1.1 The influence of temperature on graphene quality 4.1.2 The priority effect of CVD setting parameters on graphene's UTS 4.2 Analysis of PEI-modified GO/GO composite membrane 4.2.1 The role of hydrogen bonding, electrostatic attraction and carbon bonding in laminated composite membrane 4.2.2 The fabricated factors' influence to the composite's UTS 4.3 The comparison of resistivity between graphene and PEI/GO composite Chapter 5 Conclusion and future work 5.1 Conclusion 5.2 Future work Bibliography
X iv :2 01 2. 13 15 3v 1 [ co nd -m at .m es -h al l] 2 4 D ec 2 02 0 Signature of multilayer gra... more X iv :2 01 2. 13 15 3v 1 [ co nd -m at .m es -h al l] 2 4 D ec 2 02 0 Signature of multilayer graphene strain-controlled domain walls in quantum Hall effect Paul Anderson, a) Yifan Huang, a) Yuanjun Fan, Sara Qubbaj, Sinisa Coh, Qin Zhou, and Claudia Ojeda-Aristizabal Department of Physics and Astronomy, California State University Long Beach, Long Beach, California 90840, USA Department of Mechanical and Materials Engineering, University of Nebraska, Lincoln 68588-0526, Nebraska, USA Department of Mechanical Engineering and Materials Science and Engineering Program, University of California, Riverside, Riverside, CA, 92521 USA
Abstract Hydrogen embrittlement (HE) is a significant problem for many metal alloys leading to th... more Abstract Hydrogen embrittlement (HE) is a significant problem for many metal alloys leading to the degradation of mechanical strength and lifetime. Here we report that a graphene coating deposited by chemical vapor deposition can effectively protect nickel against hydrogen embrittlement. We find the degree of protection depends strongly on the graphene synthesis condition. Using ethanol as the carbon feedstock and a high cooling rate are essential in achieving effective protection. To reveal the mechanism, hydrogen permeation tests are performed, and the permeation current analyzed on different samples. Additional characterization such as optical transmission, Raman spectroscopy, and mechanical strength tests are also performed on the graphene coating. We propose that hydrogen permeates graphene in two alternating steps – transport through in-plane defects and intercalation which expands the interlayer spacing. This work demonstrates that graphene is an effective coating against HE and points out the direction to further improve the protection effectiveness.
Domain walls, topological defects that define the frontier between regions of different stacking ... more Domain walls, topological defects that define the frontier between regions of different stacking in multilayer graphene, have proved to host exciting physics. The ability of tuning these topological defects in-situ in an electronic transport experiment brings a wealth of possibilities in terms of fundamental understanding of domain walls as well as for electronic applications. Here, we demonstrate through a MEMS (microelectromechanical system) actuator and magnetoresistance measurements the effect of domain walls in multilayer graphene quantum Hall effect. Reversible and controlled uniaxial strain triggers these topological defects, manifested as new quantum Hall effect plateaus as well as a discrete and reversible modulation of the current across the device. Our findings are supported by theoretical calculations and constitute the first indication of the in-situ tuning of topological defects in multilayer graphene probed through electronic transport, opening the way to the use of reversible topological defects in electronic applications. a) PA and YH contributed equally to this work.
X iv :s ub m it/ 35 00 04 6 [ co nd -m at .m es -h al l] 2 4 D ec 2 02 0 Signature of multilayer ... more X iv :s ub m it/ 35 00 04 6 [ co nd -m at .m es -h al l] 2 4 D ec 2 02 0 Signature of multilayer graphene strain-controlled domain walls in quantum Hall effect Paul Anderson, a) Yifan Huang, a) Yuanjun Fan, Sara Qubbaj, Sinisa Coh, Qin Zhou, and Claudia Ojeda-Aristizabal Department of Physics and Astronomy, California State University Long Beach, Long Beach, California 90840, USA Department of Mechanical and Materials Engineering, University of Nebraska, Lincoln 68588-0526, Nebraska, USA Department of Mechanical Engineering and Materials Science and Engineering Program, University of California, Riverside, Riverside, CA, 92521 USA
Table of Contents List of Figures List of Tables Chapter 1 Introduction and background 1.1 Graphi... more Table of Contents List of Figures List of Tables Chapter 1 Introduction and background 1.1 Graphite and Graphene 1.2 Graphene-based composite 1.3 Synthesis, fabrication and analysis 1.4 Application Chapter 2 Synthesis, isolation, and characterization of multi-layer graphene membrane 2.1 Growth mechanism 2.2 Synthesizing graphene membrane 2.2.1 Experimental apparatus of CVD 2.2.2 Mass flow ratio calculation 2.3 Isolation of graphene membrane 2.3.1 Traditional chemical route 2.3.2 Improved electrochemical route 2.3.3 Suspending the membrane and tension adjustment 2.4 Characterization of suspended graphene membrane 2.4.1 Raman spectrum 2.4.2 Thickness and uniformity measured by optical transmissivity microscopy 2.4.3 Ultimate tensile strength measurement and calculation 2.4.4 Resistivity measurement and calculation vi Chapter 3 Synthesis of graphene-based composite membrane 3.1 The ultimate tensile strength (UTS) of membrane affected by types of interaction bonding and fabrication methods 3.2 Fabricate graphene-based composite membrane 3.2.1 The principle of spin coating 3.2.2 Polyethyleneimine (PEI) modified GO composite membrane by spin coating 3.3 Evaluation of the composite membrane 3.3.1 Thickness measurement by AFM 3.3.2 UTS and resistivity measurement and calculation Chapter 4 Results and discussion 4.1 Analysis of graphene membrane 4.1.1 The influence of temperature on graphene quality 4.1.2 The priority effect of CVD setting parameters on graphene's UTS 4.2 Analysis of PEI-modified GO/GO composite membrane 4.2.1 The role of hydrogen bonding, electrostatic attraction and carbon bonding in laminated composite membrane 4.2.2 The fabricated factors' influence to the composite's UTS 4.3 The comparison of resistivity between graphene and PEI/GO composite Chapter 5 Conclusion and future work 5.1 Conclusion 5.2 Future work Bibliography
X iv :2 01 2. 13 15 3v 1 [ co nd -m at .m es -h al l] 2 4 D ec 2 02 0 Signature of multilayer gra... more X iv :2 01 2. 13 15 3v 1 [ co nd -m at .m es -h al l] 2 4 D ec 2 02 0 Signature of multilayer graphene strain-controlled domain walls in quantum Hall effect Paul Anderson, a) Yifan Huang, a) Yuanjun Fan, Sara Qubbaj, Sinisa Coh, Qin Zhou, and Claudia Ojeda-Aristizabal Department of Physics and Astronomy, California State University Long Beach, Long Beach, California 90840, USA Department of Mechanical and Materials Engineering, University of Nebraska, Lincoln 68588-0526, Nebraska, USA Department of Mechanical Engineering and Materials Science and Engineering Program, University of California, Riverside, Riverside, CA, 92521 USA
Abstract Hydrogen embrittlement (HE) is a significant problem for many metal alloys leading to th... more Abstract Hydrogen embrittlement (HE) is a significant problem for many metal alloys leading to the degradation of mechanical strength and lifetime. Here we report that a graphene coating deposited by chemical vapor deposition can effectively protect nickel against hydrogen embrittlement. We find the degree of protection depends strongly on the graphene synthesis condition. Using ethanol as the carbon feedstock and a high cooling rate are essential in achieving effective protection. To reveal the mechanism, hydrogen permeation tests are performed, and the permeation current analyzed on different samples. Additional characterization such as optical transmission, Raman spectroscopy, and mechanical strength tests are also performed on the graphene coating. We propose that hydrogen permeates graphene in two alternating steps – transport through in-plane defects and intercalation which expands the interlayer spacing. This work demonstrates that graphene is an effective coating against HE and points out the direction to further improve the protection effectiveness.
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