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Local heat current flow in ballistic phonon transport of graphene nanoribbons
Yin-Jie Chen and Jing-Tao Lü
Phys. Rev. B 110, 035422 – Published 19 July 2024
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Abstract
Utilizing the nonequilibrium Green's function method, we study the local heat current flow of phonons in nanoscale ballistic graphene nanoribbon, where boundary scattering leads to the formation of atomic-scale current vortices. We further map out the atomic temperature distribution in the ribbon with Büttiker's probe approach. From the heat current and temperature distribution, we observe inverted temperature response in the ribbon, where the heat current direction goes from the colder to the hotter region. Moreover, we show that atomic scale defect can generate heat vortex at certain frequency, but it is averaged out when including contributions from all the phonon modes. Meanwhile, our results have recovered residual-resistivity dipole features manifested at the vicinity of local defects. These results extend the study of local heat vortex and negative temperature response in the bulk hydrodynamic regime to the atomic-scale ballistic regime, further confirming boundary scattering is crucial to generate backflow of heat current.
- Received 2 March 2024
- Revised 21 June 2024
- Accepted 24 June 2024
DOI:https://doi.org/10.1103/PhysRevB.110.035422
©2024 American Physical Society
Physics Subject Headings (PhySH)
- Research Areas
Ballistic transportHeat transferPhononsQuantum transportThermal properties
- Physical Systems
Graphene
- Techniques
Nonequilibrium Green's function
Statistical Physics & Thermodynamics
Authors & Affiliations
- School of Physics, Institute for Quantum Science and Engineering and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
- *Contact author: jtlu@hust.edu.cn
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Issue
Vol. 110, Iss. 3 — 15 July 2024
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Images
Figure 1
A sketch of the two terminal graphene nanoribbons. The reservoirs ( and ) are connected to the ribbon through narrower leads, such that heat can be locally injected or extracted from the ribbon. , and are geometric parameters.
Figure 2
Spatial pattern of local heat current (a)and local temperature (b)for a temperature bias of K, K. The coupling strength of the system and the temperature probe is meV. Geometric parameters: and .
Figure 3
Detailed profile of Fig.2. (a)Local heat flux across the vertical dashed line cut in Fig.2. The cell position is counted from bottom to top along the line cut. (b)Local temperature of the atoms on the left and right vertical border of the ribbon. The selected atoms are marked by the gray dashed boxes in Fig.2. The atom site in the middle is set to be position 0. Dashed line: average temperature in the ribbon. (c)Local temperature of the atoms shown in Fig.2with same color markers as a function of the coupling parameter .
Figure 4
Local heat flux in the ribbon with mass disorder, where is the disorder strength. The disordered current pattern is averaged from 50 ensembles. The rest of the parameters are the same in Fig.2.
Figure 5
Thermal profile in a narrow ribbon. (a)Local heat current. (b)Local temperature. Geometric parameters: and . The rest of the settings are the same as Fig.2.
Figure 6
Zigzag graphene nanoribbon with defects. is the only parameter to mark its width. (a)A sketch of the ribbon and defects. The defect is placed at the middle marked by the purple box. (b)Transmission of zigzag graphene nanoribbon with Stone-Wales and defects. Insets show phonon modes with zero transmission.
Figure 7
Local heat current and temperature of zigzag graphene nanoribbon with Stone-Wales (SW) (a), (c), (e) and (b), (d), (f) defect. Averaged local temperature in (a)and (b)is calculated by the atoms sharing the same horizontal coordinate, from the left reservoir to the right. Temperature distribution near the defect is demonstrated by light blue lines, extracted from the shaded region at the middle of the nanoribbon in Fig.6. (c), (d)Local heat current through the defect atoms are given by , the color gradient is consistent with . (e), (f) Frequency resolved at (e) and 150.02meV (f). These frequencies are found in the insets of Fig.6.