Spindependent Seebeck effects in a graphene nanoribbon coupled to two square lattice ferromagnetic leads
Abstract
We theoretically investigate spindependent Seebeck effects for a system consisting of a narrow graphene nanoribbon (GNR) contacted to square lattice ferromagnetic (FM) electrodes with noncollinear magnetic moments. Both zigzagedge graphene nanoribbons (ZGNRs) and armchairedge graphene nanoribbons (AGNRs) were considered. Compared with our previous work with twodimensional honeycomblattice FM leads, a more realistic model of twodimensional squarelattice FM electrodes is adopted here. Using the nonequilibrium Green's function method combining with the tightbinding Hamiltonian, it is demonstrated that both the charge Seebeck coefficient S{sub C} and the spindependent Seebeck coefficient S{sub S} strongly depend on the geometrical contact between the GNR and the leads. In our previous work, S{sub C} for a semiconducting 15AGNR system near the Dirac point is two orders of magnitude larger than that of a metallic 17AGNR system. However, S{sub C} is the same order of magnitude for both metallic 17AGNR and semiconducting 15AGNR systems in the present paper because of the lack of a transmission energy gap for the 15AGNR system. Furthermore, the spindependent Seebeck coefficient S{sub S} for the systems with 20ZGNR, 17AGNR, and 15AGNR is of the same order of magnitude and its maximum absolute value can reach 8 μV/K. The spindependent Seebeck effects are notmore »
 Authors:
 Department of Physics, Shaoyang University, Shaoyang 422001 (China)
 Department of Physics and Key Laboratory for LowDimensional Structures and Quantum Manipulation (Ministry of Education), Hunan Normal University, Changsha 410081 (China)
 Hunan Key Laboratory for MicroNano Energy Materials and Device and Department of Physics, Xiangtan University, Xiangtan 411105 (China)
 Publication Date:
 OSTI Identifier:
 22399256
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 10; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COMPARATIVE EVALUATIONS; ELECTRODES; ENERGY GAP; FERROMAGNETIC MATERIALS; FERROMAGNETISM; GRAPHENE; HAMILTONIANS; MAGNETIC MOMENTS; MAGNETIZATION; NANOSTRUCTURES; SEMICONDUCTOR MATERIALS; SPIN; SPIN ORIENTATION; TETRAGONAL LATTICES; TWODIMENSIONAL CALCULATIONS; TWODIMENSIONAL SYSTEMS
Citation Formats
Zhou, Benhu, Email: zhoubenhu@163.com, Zeng, Yangsu, Zhou, Benliang, Zhou, Guanghui, Email: ghzhou@hunnu.edu.cn, and Ouyang, Tao. Spindependent Seebeck effects in a graphene nanoribbon coupled to two square lattice ferromagnetic leads. United States: N. p., 2015.
Web. doi:10.1063/1.4914486.
Zhou, Benhu, Email: zhoubenhu@163.com, Zeng, Yangsu, Zhou, Benliang, Zhou, Guanghui, Email: ghzhou@hunnu.edu.cn, & Ouyang, Tao. Spindependent Seebeck effects in a graphene nanoribbon coupled to two square lattice ferromagnetic leads. United States. doi:10.1063/1.4914486.
Zhou, Benhu, Email: zhoubenhu@163.com, Zeng, Yangsu, Zhou, Benliang, Zhou, Guanghui, Email: ghzhou@hunnu.edu.cn, and Ouyang, Tao. 2015.
"Spindependent Seebeck effects in a graphene nanoribbon coupled to two square lattice ferromagnetic leads". United States.
doi:10.1063/1.4914486.
@article{osti_22399256,
title = {Spindependent Seebeck effects in a graphene nanoribbon coupled to two square lattice ferromagnetic leads},
author = {Zhou, Benhu, Email: zhoubenhu@163.com and Zeng, Yangsu and Zhou, Benliang and Zhou, Guanghui, Email: ghzhou@hunnu.edu.cn and Ouyang, Tao},
abstractNote = {We theoretically investigate spindependent Seebeck effects for a system consisting of a narrow graphene nanoribbon (GNR) contacted to square lattice ferromagnetic (FM) electrodes with noncollinear magnetic moments. Both zigzagedge graphene nanoribbons (ZGNRs) and armchairedge graphene nanoribbons (AGNRs) were considered. Compared with our previous work with twodimensional honeycomblattice FM leads, a more realistic model of twodimensional squarelattice FM electrodes is adopted here. Using the nonequilibrium Green's function method combining with the tightbinding Hamiltonian, it is demonstrated that both the charge Seebeck coefficient S{sub C} and the spindependent Seebeck coefficient S{sub S} strongly depend on the geometrical contact between the GNR and the leads. In our previous work, S{sub C} for a semiconducting 15AGNR system near the Dirac point is two orders of magnitude larger than that of a metallic 17AGNR system. However, S{sub C} is the same order of magnitude for both metallic 17AGNR and semiconducting 15AGNR systems in the present paper because of the lack of a transmission energy gap for the 15AGNR system. Furthermore, the spindependent Seebeck coefficient S{sub S} for the systems with 20ZGNR, 17AGNR, and 15AGNR is of the same order of magnitude and its maximum absolute value can reach 8 μV/K. The spindependent Seebeck effects are not very pronounced because the transmission coefficient weakly depends on spin orientation. Moreover, the spindependent Seebeck coefficient is further suppressed with increasing angle between the relative alignments of magnetization directions of the two leads. Additionally, the spindependent Seebeck coefficient can be strongly suppressed for larger disorder strength. The results obtained here may provide valuable theoretical guidance in the experimental design of heat spintronic devices.},
doi = {10.1063/1.4914486},
journal = {Journal of Applied Physics},
number = 10,
volume = 117,
place = {United States},
year = 2015,
month = 3
}

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