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De A, Ghosh A, Mandal R, Ogale S, Nair S. Temperature Dependence of the Spin Seebeck Effect in a Mixed Valent Manganite. PHYSICAL REVIEW LETTERS 2020; 124:017203. [PMID: 31976695 DOI: 10.1103/physrevlett.124.017203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 11/12/2019] [Indexed: 06/10/2023]
Abstract
We report on temperature dependent measurements of the longitudinal spin Seebeck effect (LSSE) in the mixed valent manganite La_{0.7}Ca_{0.3}MnO_{3}. By disentangling the contribution arising due to the anisotropic Nernst effect, we observe that in the low temperature regime, the LSSE exhibits a T^{0.5} dependence, which matches well with that predicted by the magnon-driven spin current model. Across the double exchange driven paramagnetic-ferromagnetic transition, the LSSE exponent is significantly higher than the magnetization one, and also depends on the thickness of the spin-to-charge conversion layer. These observations highlight the importance of individually ascertaining the temperature evolution of different mechanisms-especially the spin mixing conductance-which contribute to the measured spin Seebeck signal.
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Affiliation(s)
- Avirup De
- Department of Physics, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune, Maharashtra-411008, India
| | - Arup Ghosh
- Department of Physics, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune, Maharashtra-411008, India
| | - Rajesh Mandal
- Department of Physics, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune, Maharashtra-411008, India
| | - Satishchandra Ogale
- Department of Physics, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune, Maharashtra-411008, India
- Centre for Energy Science, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune, Maharashtra-411008, India
| | - Sunil Nair
- Department of Physics, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune, Maharashtra-411008, India
- Centre for Energy Science, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune, Maharashtra-411008, India
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Zhu L, Li B, Ma H, Qian M, Yao K. Electrical-field tuned thermoelectric performance of graphene nanoribbon with sawtooth edges. NANOTECHNOLOGY 2019; 30:445204. [PMID: 31349241 DOI: 10.1088/1361-6528/ab35f5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
By using first-principle calculations combined with the non-equilibrium Green's function approach, we report that a vertical electrical field can modulate the thermoelectric performance of a graphene nanoribbon with sawtooth edges. The results show that the sawtooth graphene nanoribbon exhibits the spin-dependent Seebeck effect under the temperature gradients, and is strengthened by increasing the width of the sawtooth graphene nanoribbon. When the vertical electrical field is applied to the device, the spin-dependent Seebeck effect can also be enhanced. The vertical electrical field can modulate the device transferring from hole-conducting to electron-conducting. This opens up the possibility of tuning the thermal transport properties of the device by the electrical field.
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Affiliation(s)
- Lin Zhu
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
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Seifert TS, Jaiswal S, Barker J, Weber ST, Razdolski I, Cramer J, Gueckstock O, Maehrlein SF, Nadvornik L, Watanabe S, Ciccarelli C, Melnikov A, Jakob G, Münzenberg M, Goennenwein STB, Woltersdorf G, Rethfeld B, Brouwer PW, Wolf M, Kläui M, Kampfrath T. Femtosecond formation dynamics of the spin Seebeck effect revealed by terahertz spectroscopy. Nat Commun 2018; 9:2899. [PMID: 30042421 PMCID: PMC6057952 DOI: 10.1038/s41467-018-05135-2] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 06/13/2018] [Indexed: 11/09/2022] Open
Abstract
Understanding the transfer of spin angular momentum is essential in modern magnetism research. A model case is the generation of magnons in magnetic insulators by heating an adjacent metal film. Here, we reveal the initial steps of this spin Seebeck effect with <27 fs time resolution using terahertz spectroscopy on bilayers of ferrimagnetic yttrium iron garnet and platinum. Upon exciting the metal with an infrared laser pulse, a spin Seebeck current js arises on the same ~100 fs time scale on which the metal electrons thermalize. This observation highlights that efficient spin transfer critically relies on carrier multiplication and is driven by conduction electrons scattering off the metal–insulator interface. Analytical modeling shows that the electrons’ dynamics are almost instantaneously imprinted onto js because their spins have a correlation time of only ~4 fs and deflect the ferrimagnetic moments without inertia. Applications in material characterization, interface probing, spin-noise spectroscopy and terahertz spin pumping emerge. Probing spin pumping in the terahertz regime allows one to reveal its initial elementary steps. Here, the authors show that the formation of the spin Seebeck current in YIG/Pt critically relies on hot thermalized metal electrons because they impinge on the metal-insulator interface with maximum noise.
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Affiliation(s)
- Tom S Seifert
- Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany.,Department of Physics, Freie Universität Berlin, 14195, Berlin, Germany
| | - Samridh Jaiswal
- Institute of Physics, Johannes Gutenberg University Mainz, 55099, Mainz, Germany.,Singulus Technologies AG, 63796, Kahl am Main, Germany
| | - Joseph Barker
- Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - Sebastian T Weber
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, 67663, Kaiserslautern, Germany
| | - Ilya Razdolski
- Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany
| | - Joel Cramer
- Institute of Physics, Johannes Gutenberg University Mainz, 55099, Mainz, Germany
| | - Oliver Gueckstock
- Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany
| | - Sebastian F Maehrlein
- Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany
| | - Lukas Nadvornik
- Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany.,Department of Physics, Freie Universität Berlin, 14195, Berlin, Germany
| | - Shun Watanabe
- Department of Advanced Materials Science, School of Frontier Sciences, University of Tokyo, Chiba, 277-8561, Japan
| | - Chiara Ciccarelli
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Alexey Melnikov
- Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany.,Institute of Physics, Martin-Luther-Universität Halle, 06120, Halle, Germany
| | - Gerhard Jakob
- Institute of Physics, Johannes Gutenberg University Mainz, 55099, Mainz, Germany
| | - Markus Münzenberg
- Institut für Physik, Universität Greifswald, 17489, Greifswald, Germany
| | - Sebastian T B Goennenwein
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062, Dresden, Germany
| | - Georg Woltersdorf
- Institute of Physics, Martin-Luther-Universität Halle, 06120, Halle, Germany
| | - Baerbel Rethfeld
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, 67663, Kaiserslautern, Germany
| | - Piet W Brouwer
- Department of Physics, Freie Universität Berlin, 14195, Berlin, Germany
| | - Martin Wolf
- Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany
| | - Mathias Kläui
- Institute of Physics, Johannes Gutenberg University Mainz, 55099, Mainz, Germany
| | - Tobias Kampfrath
- Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany. .,Department of Physics, Freie Universität Berlin, 14195, Berlin, Germany.
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Interface-induced spin Hall magnetoresistance enhancement in Pt-based tri-layer structure. Sci Rep 2018; 8:108. [PMID: 29311703 PMCID: PMC5758776 DOI: 10.1038/s41598-017-18369-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 12/01/2017] [Indexed: 11/08/2022] Open
Abstract
In this study, we integrated bilayer structure of covered Pt on nickel zinc ferrite (NZFO) and CoFe/Pt/NZFO tri-layer structure by pulsed laser deposition system for a spin Hall magnetoresistance (SMR) study. In the bilayer structure, the angular-dependent magnetoresistance (MR) results indicate that Pt/NZFO has a well-defined SMR behavior. Moreover, the spin Hall angle and the spin diffusion length, which were 0.0648 and 1.31 nm, respectively, can be fitted by changing the Pt thickness in the longitudinal SMR function. Particularly, the MR ratio of the bilayer structure (Pt/NZFO) has the highest changing ratio (about 0.135%), compared to the prototype structure Pt/Y3Fe5O12 (YIG) because the NZFO has higher magnetization. Meanwhile, the tri-layer samples (CoFe/Pt/NZFO) indicate that the MR behavior is related with CoFe thickness as revealed in angular-dependent MR measurement. Additionally, comparison between the tri-layer structure with Pt/NZFO and CoFe/Pt bilayer systems suggests that the SMR ratio can be enhanced by more than 70%, indicating that additional spin current should be injected into Pt layer.
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Wu DD, Liu QB, Fu HH, Wu R. How to realize a spin-dependent Seebeck diode effect in metallic zigzag γ-graphyne nanoribbons? NANOSCALE 2017; 9:18334-18342. [PMID: 29143060 DOI: 10.1039/c7nr06448a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The spin-dependent Seebeck effect (SDSE) is one of the core topics of spin caloritronics. In the traditional device designs of spin-dependent Seebeck rectifiers and diodes, finite spin-dependent band gaps of materials are required to realize the on-off characteristic in thermal spin currents, and nearly zero charge current should be achieved to reduce energy dissipation. Here, we propose that two ferromagnetic zigzag γ-graphyne nanoribbons (ZγGNRs) without any spin-dependent band gaps around the Fermi level can not only exhibit the SDSE, but also display rectifier and diode effects in thermal spin currents characterized by threshold temperatures, which originates from the compensation effect occurring in spin-dependent transmissions but not from the spin-splitting band gaps in materials. The metallic characteristics of ZγGNRs bring about an advantage that the gate voltage is an effective route to adjust the symmetry of spin-splitting bands to obtain pure thermal spin currents. The results provide a new mechanism to realize spin-Seebeck rectifier and diode effects in 2D materials and expand material candidates towards spin-Seebeck device applications.
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Affiliation(s)
- Dan-Dan Wu
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China.
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