Spin-dependent thermo-galvanic effects: experiment
Final Report Abstract
As a part of Priority Programme 1538: Spin-Caloric Transport, the research project Spindependent thermo-galvanic effects: experiment was dedicated to the investigation of spin caloritronic transport phenomena in thin films and heterostructures. The properties of pure spin currents in magnetic insulators hereby played a key role. The most prominent results from the project work are (i) The first experimental observation of the spin Nernst effect – i.e., of a thermally driven pure spin current flowing in a direction perpendicular to both the applied thermal gradient and the sample’s magnetization. (ii) The discovery (in the first project phase) and detailed investigation (in the second project phase) of the spin Hall magnetoresistance effect, which arises from spin transfer across a magnetic insulator/metal interface. In particular, we could show that the spin Hall magnetoresistance is not limited to ’simple’ collinear ferro- or ferrimagnets, but persists in non-collinear spin structures, in antiferromagnets, and in paramagnets. (iii) The systematic investigation of the spin Seebeck effect – i.e., of thermal spin currents flowing along a temperature gradient – in collinear and non-collinear magnetic insulators, as well as of the dynamics inherent to the spin Seebeck effect. Our results here show that a broad spectrum of magnons, as well as different magnon branches, must be taken into account to understand spin Seebeck physics. (iv) The observation of spin-current driven spin waves with very short wavelength in magnetic insulator/magnetic metal heterostructures, suggesting a new means to generate spin waves in the exchange regime. (v) The detection of pure spin currents ’pumped’ resonantly by magnon-photon-polariton modes in the strong coupling regime, in which the magnonic and photonic modes hybridize strongly. (vi) The quantitative investigation of the Gilbert damping of standing spin waves in yttrium iron garnet crystals, demonstrating that all spin waves share one and the same Gilbert damping constant. (vii) The pulsed laser deposition of high-quality thin films and heterostructures made from magnetic garnets such as yttrium iron garnet, gadolinium iron garnet, dysprosium iron garnet, etc., as well as of antiferromagnetic insulator films such as NiO and Fe2O3. (viii) Last but not least the detection of a strong ’topological’ component in the anomalous Hall and the anomalous Nernst response in magnetic Weyl semimetal thin films. The corresponding data show that spin caloritronic transport effects can be very large and exciting in materials with ’topological’ band structure properties or spin configurations. In a nutshell, we thus have investigated spin caloric transport and pure spin current flow in a variety of magnetic systems and experimental configurations. Our results corroborate the notion proposed within the new field of spin caloritronics, that the transport of charge, heat and spin degrees of freedom should be treated on equal footing. This implies that long established thermo-electric phenomena such as the Seebeck effect and Nernst effect must have ’spin’ counterparts, in which a thermal drive results in a pure spin angular momentum flow. The spin Seebeck and spin Nernst effects are two such new ’spin’-based transport phenomena. Vice versa, our results allowed to clarify several basic questions related to spin caloritronic transport. Hereby, collaborations both within SPP 1538 and on an international level, and in both theory and experiment, were of key importance.
Publications
- Non-local magnetoresistance in YIG/Pt nanostructures, Appl. Phys. Lett. 107, 172405 (2015)
S. T. B. Goennenwein, R. Schlitz, M. Pernpeintner, K. Ganzhorn, M. Althammer, R. Gross, H. Huebl
(See online at https://doi.org/10.1063/1.4935074) - Magnon-based logic in a multi-terminal YIG/Pt nanostructure, Appl. Phys. Lett. 109, 022405 (2016)
K. Ganzhorn, S. Klingler, T. Wimmer, S. Geprägs, R. Gross, H. Huebl, S. T. B. Goennenwein
(See online at https://doi.org/10.1063/1.4958893) - Origin of the spin Seebeck effect in compensated ferrimagnets, Nat. Commun. 7, 10452 (2016)
S. Geprägs, A. Kehlberger, F. Della Coletta, Z. Qiu, E.-J. Guo, T. Schulz, C. Mix, S. Meyer, A. Kamra, M. Althammer, H. Huebl, G. Jakob, Y. Ohnuma, H. Adachi, J. Barker, S. Maekawa, G. E. W. Bauer, E. Saitoh, R. Gross, S. T. B. Goennenwein, M. Kläui
(See online at https://doi.org/10.1038/ncomms10452) - Spin Hall magnetoresistance in a canted ferrimagnet, Phys. Rev. B 94, 094401 (2016)
K. Ganzhorn, J. Barker, R. Schlitz, B. A. Piot, K. Ollefs, F. Guillou, F. Wilhelm, A. Rogalev, M. Opel, M. Althammer, S. Geprägs, H. Huebl, R. Gross, G. E. W. Bauer, S. T. B. Goennenwein
(See online at https://doi.org/10.1103/PhysRevB.94.094401) - Spin pumping in strongly coupled magnon-photon systems, Phys. Rev. B 94, 054433 (2016)
H. Maier-Flaig, M. Harder, R. Gross, H. Huebl, S. T. B. Goennenwein
(See online at https://doi.org/10.1103/PhysRevB.94.054433) - Spin Seebeck effect at microwave frequencies, Phys. Rev. B 93, 224430 (2016)
M. Schreier, F. Kramer, H. Huebl, S. Geprägs, R. Gross, S. T. B. Goennenwein, T. Noack, T. Langner, A. A. Serga, B. Hillebrands, V. I. Vasyuchka
(See online at https://doi.org/10.1103/PhysRevB.93.224430) - Theory of spin Hall magnetoresistance (SMR) and related phenomena, J. Phys.: Condens. Matter 28, 103004 (2016)
Y.-T. Chen, S. Takahashi, H. Nakayama, M. Althammer, S. T. B. Goennenwein, E. Saitoh, G. E. W. Bauer
(See online at https://doi.org/10.1088/0953-8984/28/10/103004) - Gilbert damping of magnetostatic modes in a yttrium iron garnet sphere, Appl. Phys. Lett. 110, 092409 (2017)
S. Klingler, H. Maier-Flaig, C. Dubs, O. Surzhenko, R. Gross, H. Huebl, S. T. B. Goennenwein, M. Weiler
(See online at https://doi.org/10.1063/1.4977423) - Magnon Mode Selective Spin Transport in Compensated Ferrimagnets, Nano Lett. 17, 3334 (2017)
J. Cramer, E.-J. Guo, S. Geprägs, A. Kehlberger, Y. P. Ivanov, K. Ganzhorn, F. Della Coletta, M. Althammer, H. Huebl, R. Gross, J. Kosel, M. Kläui, S. T. B. Goennenwein
(See online at https://doi.org/10.1021/acs.nanolett.6b04522) - Observation of the spin Nernst effect, Nat. Mater. 16, 977 (2017)
S. Meyer, Y.-T. Chen, S. Wimmer, M. Althammer, T. Wimmer, R. Schlitz, S. Geprägs, H. Huebl, D. Ködderitzsch, H. Ebert, G. E. W. Bauer, R. Gross, S. T. B. Goennenwein
(See online at https://doi.org/10.1038/nmat4964) - Temperature-dependent magnetic damping of yttrium iron garnet spheres, Phys. Rev. B 95, 214423 (2017)
H. Maier-Flaig, S. Klingler, C. Dubs, O. Surzhenko, R. Gross, M. Weiler, H. Huebl, S. T. B. Goennenwein
(See online at https://doi.org/10.1103/PhysRevB.95.214423) - Tunable magnon-photon coupling in a compensating ferrimagnet—from weak to strong coupling, Appl. Phys. Lett. 110, 132401 (2017)
H. Maier-Flaig, M. Harder, S. Klingler, Z. Qiu, E. Saitoh, M. Weiler, S. Geprägs, R. Gross, S. T. B. Goennenwein, H. Huebl
(See online at https://doi.org/10.1063/1.4979409) - Evolution of the spin Hall magnetoresistance in Cr2 O3 /Pt bilayers close to the Néel temperature, Appl. Phys. Lett. 112, 132401 (2018)
R. Schlitz, T. Kosub, A. Thomas, S. Fabretti, K. Nielsch, D. Makarov, S. T. B. Goennenwein
(See online at https://doi.org/10.1063/1.5019934) - Femtosecond formation dynamics of the spin Seebeck effect revealed by terahertz spectroscopy, Nat. Commun. 9, 2899 (2018)
T. S. Seifert, S. Jaiswal, J. Barker, S. T. Weber, I. Razdolski, J. Cramer, O. Gueckstock, S. F. Maehrlein, L. Nadvornik, S. Watanabe, C. Ciccarelli, A. Melnikov, G. Jakob, M. Münzenberg, S. T. B. Goennenwein, G. Woltersdorf, B. Rethfeld, P. W. Brouwer, M. Wolf, M. Kläui, T. Kampfrath
(See online at https://doi.org/10.1038/s41467-018-05135-2) - Large anomalous Nernst effect in thin films of the Weyl semimetal Co2 MnGa, Appl. Phys. Lett. 113, 212405 (2018)
H. Reichlova, R. Schlitz, S. Beckert, P. Swekis, A. Markou, Y. Chen, D. Kriegner, S. Fabretti, G. Park, A. Niemann, S. Sudheendra, A. Thomas, K. Nielsch, C. Felser, S. T. B. Goennenwein
(See online at https://doi.org/10.1063/1.5048690) - Note: Derivative divide, a method for the analysis of broadband ferromagnetic resonance in the frequency domain, Rev. Sci. Instr. 89, 076101 (2018)
H. Maier-Flaig, S. T. B. Goennenwein, R. Ohshima, M. Shiraishi, R. Gross, H. Huebl, M. Weiler
(See online at https://doi.org/10.1063/1.5045135) - Spin Hall magnetoresistance in antiferromagnet/heavy-metal heterostructures, Phys. Rev. B 97, (2018)
J. Fischer, O. Gomonay, R. Schlitz, K. Ganzhorn, N. Vlietstra, M. Althammer, H. Huebl, M. Opel, R. Gross, S. T. B. Goennenwein, S. Geprägs
(See online at https://doi.org/10.1103/PhysRevB.97.014417) - Spin-Hall-Active Platinum Thin Films Grown Via Atomic Layer Deposition, Appl. Phys. Lett. 112, 242403 (2018)
R. Schlitz, A. A. Amusan, M. Lammel, S. Schlicht, T. Tynell, J. Bachmann, G. Woltersdorf, K. Nielsch, S. T. B. Goennenwein, A. Thomas
(See online at https://doi.org/10.1063/1.5025472) - Spin-Torque Excitation of Perpendicular Standing Spin Waves in Coupled YIG/Co Heterostructures, Phys. Rev. Lett. 120, 127201 (2018)
S. Klingler, V. Amin, S. Geprägs, K. Ganzhorn, H. Maier-Flaig, M. Althammer, H. Huebl, R. Gross, R. D. McMichael, M. D. Stiles, S. T. B. Goennenwein, M. Weiler
(See online at https://doi.org/10.1103/PhysRevLett.120.127201) - All Electrical Access to Topological Transport Features in Mn1.8 PtSn Films, Nano Lett. 19, 2366- (2019)
R. Schlitz, P. Swekis, A. Markou, H. Reichlova, M. Lammel, J. Gayles, A. Thomas, K. Nielsch, C. Felser, S. T. B. Goennenwein
(See online at https://doi.org/10.1021/acs.nanolett.8b05042)
