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Review on Magnetism in Catalysis: From Theory to PEMFC Applications of 3d Metal Pt-Based Alloys. Int J Mol Sci 2022; 23:ijms232314768. [PMID: 36499096 PMCID: PMC9739051 DOI: 10.3390/ijms232314768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/18/2022] [Accepted: 11/22/2022] [Indexed: 11/29/2022] Open
Abstract
The relationship between magnetism and catalysis has been an important topic since the mid-20th century. At present time, the scientific community is well aware that a full comprehension of this relationship is required to face modern challenges, such as the need for clean energy technology. The successful use of (para-)magnetic materials has already been corroborated in catalytic processes, such as hydrogenation, Fenton reaction and ammonia synthesis. These catalysts typically contain transition metals from the first to the third row and are affected by the presence of an external magnetic field. Nowadays, it appears that the most promising approach to reach the goal of a more sustainable future is via ferromagnetic conducting catalysts containing open-shell metals (i.e., Fe, Co and Ni) with extra stabilization coming from the presence of an external magnetic field. However, understanding how intrinsic and extrinsic magnetic features are related to catalysis is still a complex task, especially when catalytic performances are improved by these magnetic phenomena. In the present review, we introduce the relationship between magnetism and catalysis and outline its importance in the production of clean energy, by describing the representative case of 3d metal Pt-based alloys, which are extensively investigated and exploited in PEM fuel cells.
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Abstract
The Hall effect can be extended by inducing a temperature gradient in lieu of electric field that is known as the Nernst (-Ettingshausen) effect. The recently discovered spin Nernst effect in heavy metals continues to enrich the picture of Nernst effect-related phenomena. However, the collection would not be complete without mentioning the valley degree of freedom benchmarked by the valley Hall effect. Here we show the experimental evidence of its missing counterpart, the valley Nernst effect. Using millimeter-sized WSe\documentclass[12pt]{minimal}
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\begin{document}$${}_{2}$$\end{document}2 mono-multi-layers and the ferromagnetic resonance-spin pumping technique, we are able to apply a temperature gradient by off-centering the sample in the radio frequency cavity and address a single valley through spin-valley coupling. The combination of a temperature gradient and the valley polarization leads to the valley Nernst effect in WSe\documentclass[12pt]{minimal}
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\begin{document}$${}_{2}$$\end{document}2 that we detect electrically at room temperature. The valley Nernst coefficient is in good agreement with the predicted value. Atomically thin transition metal dichalcogenides possess a valley degree of freedom, which could enrich the physics underpinning the conventional Nernst effect observed in traditional solids. Here, the authors report experimental evidence of the valley Nernst effect in WSe2 at room temperature.
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Cramer J, Fuhrmann F, Ritzmann U, Gall V, Niizeki T, Ramos R, Qiu Z, Hou D, Kikkawa T, Sinova J, Nowak U, Saitoh E, Kläui M. Magnon detection using a ferroic collinear multilayer spin valve. Nat Commun 2018. [PMID: 29540718 PMCID: PMC5852167 DOI: 10.1038/s41467-018-03485-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Information transport and processing by pure magnonic spin currents in insulators is a promising alternative to conventional charge-current-driven spintronic devices. The absence of Joule heating and reduced spin wave damping in insulating ferromagnets have been suggested for implementing efficient logic devices. After the successful demonstration of a majority gate based on the superposition of spin waves, further components are required to perform complex logic operations. Here, we report on magnetization orientation-dependent spin current detection signals in collinear magnetic multilayers inspired by the functionality of a conventional spin valve. In Y3Fe5O12|CoO|Co, we find that the detection amplitude of spin currents emitted by ferromagnetic resonance spin pumping depends on the relative alignment of the Y3Fe5O12 and Co magnetization. This yields a spin valve-like behavior with an amplitude change of 120% in our systems. We demonstrate the reliability of the effect and identify its origin by both temperature-dependent and power-dependent measurements.
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Affiliation(s)
- Joel Cramer
- Institute of Physics, Johannes Gutenberg-University Mainz, 55099, Mainz, Germany.,Graduate School of Excellence Materials Science in Mainz, 55128, Mainz, Germany
| | - Felix Fuhrmann
- Institute of Physics, Johannes Gutenberg-University Mainz, 55099, Mainz, Germany
| | - Ulrike Ritzmann
- Institute of Physics, Johannes Gutenberg-University Mainz, 55099, Mainz, Germany.,Department of Physics, University of Konstanz, 78457, Konstanz, Germany
| | - Vanessa Gall
- Department of Physics, University of Konstanz, 78457, Konstanz, Germany
| | - Tomohiko Niizeki
- Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - Rafael Ramos
- Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - Zhiyong Qiu
- Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.,School of Materials Science and Engineering, Dalian University of Technology, Dalian, 116024, China
| | - Dazhi Hou
- Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - Takashi Kikkawa
- Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.,Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - Jairo Sinova
- Institute of Physics, Johannes Gutenberg-University Mainz, 55099, Mainz, Germany
| | - Ulrich Nowak
- Department of Physics, University of Konstanz, 78457, Konstanz, Germany
| | - Eiji Saitoh
- Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.,Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.,Center for Spintronics Research Network, Tohoku University, Sendai, 980-8577, Japan.,Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, 319-1195, Japan
| | - Mathias Kläui
- Institute of Physics, Johannes Gutenberg-University Mainz, 55099, Mainz, Germany. .,Graduate School of Excellence Materials Science in Mainz, 55128, Mainz, Germany.
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Sheng P, Sakuraba Y, Lau YC, Takahashi S, Mitani S, Hayashi M. The spin Nernst effect in tungsten. SCIENCE ADVANCES 2017; 3:e1701503. [PMID: 29119140 PMCID: PMC5669613 DOI: 10.1126/sciadv.1701503] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 10/04/2017] [Indexed: 06/01/2023]
Abstract
The spin Hall effect allows the generation of spin current when charge current is passed along materials with large spin-orbit coupling. It has been recently predicted that heat current in a nonmagnetic metal can be converted into spin current via a process referred to as the spin Nernst effect. We report the observation of the spin Nernst effect in W. In W/CoFeB/MgO heterostructures, we find changes in the longitudinal and transverse voltages with magnetic field when temperature gradient is applied across the film. The field dependence of the voltage resembles that of the spin Hall magnetoresistance. A comparison of the temperature gradient-induced voltage and the spin Hall magnetoresistance allows direct estimation of the spin Nernst angle. We find the spin Nernst angle of W to be similar in magnitude but opposite in sign to its spin Hall angle. Under an open-circuit condition, this sign difference results in the spin current generation larger than otherwise. These results highlight the distinct characteristics of the spin Nernst and spin Hall effects, providing pathways to explore materials with unique band structures that may generate large spin current with high efficiency.
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Affiliation(s)
- Peng Sheng
- National Institute for Materials Science, Tsukuba 305-0047, Japan
| | - Yuya Sakuraba
- National Institute for Materials Science, Tsukuba 305-0047, Japan
| | - Yong-Chang Lau
- National Institute for Materials Science, Tsukuba 305-0047, Japan
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Saburo Takahashi
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - Seiji Mitani
- National Institute for Materials Science, Tsukuba 305-0047, Japan
- Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8577, Japan
| | - Masamitsu Hayashi
- National Institute for Materials Science, Tsukuba 305-0047, Japan
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
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Reimer O, Meier D, Bovender M, Helmich L, Dreessen JO, Krieft J, Shestakov AS, Back CH, Schmalhorst JM, Hütten A, Reiss G, Kuschel T. Quantitative separation of the anisotropic magnetothermopower and planar Nernst effect by the rotation of an in-plane thermal gradient. Sci Rep 2017; 7:40586. [PMID: 28094279 PMCID: PMC5240136 DOI: 10.1038/srep40586] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 12/08/2016] [Indexed: 11/08/2022] Open
Abstract
A thermal gradient as the driving force for spin currents plays a key role in spin caloritronics. In this field the spin Seebeck effect (SSE) is of major interest and was investigated in terms of in-plane thermal gradients inducing perpendicular spin currents (transverse SSE) and out-of-plane thermal gradients generating parallel spin currents (longitudinal SSE). Up to now all spincaloric experiments employ a spatially fixed thermal gradient. Thus, anisotropic measurements with respect to well defined crystallographic directions were not possible. Here we introduce a new experiment that allows not only the in-plane rotation of the external magnetic field, but also the rotation of an in-plane thermal gradient controlled by optical temperature detection. As a consequence, the anisotropic magnetothermopower and the planar Nernst effect in a permalloy thin film can be measured simultaneously. Thus, the angular dependence of the magnetothermopower with respect to the magnetization direction reveals a phase shift, that allows the quantitative separation of the thermopower, the anisotropic magnetothermopower and the planar Nernst effect.
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Affiliation(s)
- Oliver Reimer
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Daniel Meier
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Michel Bovender
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Lars Helmich
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Jan-Oliver Dreessen
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Jan Krieft
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Anatoly S. Shestakov
- Institute of Experimental and Applied Physics, University of Regensburg, Universitätsstraße 31, 93040 Regensburg, Germany
| | - Christian H. Back
- Institute of Experimental and Applied Physics, University of Regensburg, Universitätsstraße 31, 93040 Regensburg, Germany
| | - Jan-Michael Schmalhorst
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Andreas Hütten
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Günter Reiss
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Timo Kuschel
- Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
- Physics of Nanodevices, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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