Origin of the spin Seebeck effect in compensated ferrimagnets

Geprägs, Stephan; Kehlberger, Andreas; Coletta, Francesco Della; Qiu, Zhiyong; Guo, Er‐Jia; Schulz, Thorsten; Mix, Christian; Meyer, Sibylle; Kamra, Akashdeep; Althammer, Matthias; Huebl, Hans; Jakob, G.; Ohnuma, Yuichi; Adachi, Hiroto; Barker, Joseph; Maekawa, Sadamichi; Bauer, G.; Saitoh, Eiji; Gross, Rudolf; Goennenwein, Sebastian T. B.; Kläui, Mathias

doi:10.1038/ncomms10452

Cited by 187 publications

(212 citation statements)

References 29 publications

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“…It is possible to identify spin current generation from a system like MnF 2 since there is a large abrupt change in the spin wave spectrum through the spin-flop transition, which can be inferred from antiferromagnetic resonance experiments [42]. Both theoretical and experimental evidence for changes in the spin Seebeck effect due to changes in magnon branch degeneracy have been reported for compensated ferrimagnetic systems [8,43]. This type of change in the MnF 2 spin-flop transition could lead to a change in the net spin current and an abrupt change in the voltage response like the one observed in our devices.…”

Section: Prl 116 097204 (2016) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%

Antiferromagnetic Spin Seebeck Effect

et al. 2016

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We report on the observation of the spin Seebeck effect in antiferromagnetic MnF2. A device scale on-chip heater is deposited on a bilayer of MnF2 (110) (30 nm)/Pt (4 nm) grown by molecular beam epitaxy on a MgF2 (110) substrate. Using Pt as a spin detector layer it is possible to measure thermally generated spin current from MnF2 through the inverse spin Hall effect. The low temperature (2 -80 K) and high magnetic field (up to 140 kOe) regime is explored. A clear spin flop transition corresponding to the sudden rotation of antiferromagnetic spins out of the easy axis is observed in the spin Seebeck signal when large magnetic fields (>9 T) are applied parallel the easy axis of the MnF2 thin film. When magnetic field is applied perpendicular to the easy axis, the spin flop transition is absent, as expected.

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Section: Prl 116 097204 (2016) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%

Antiferromagnetic Spin Seebeck Effect

et al. 2016

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“…Therefore, over the past years spin current transport has been extensively studied in paramagnetic (normal) metal (NM)/ferromagnetic insulator (FMI) hybrid structures in spin pumping, spin Seebeck effect, or spin Hall magnetoresistance (SMR) experiments. [1][2][3][4][5][6][7] In all these experiments the signal amplitude sensitively depends on the transfer of a spin current, i.e. spin angular momentum, across the NM/FMI interface and its interconversion into an electrical signal via the inverse spin Hall effect.…”

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confidence: 99%

Impact of the interface quality of Pt/YIG(111) hybrids on their spin Hall magnetoresistance

Pütter

Geprägs

Schlitz

et al. 2017

Applied Physics Letters

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We study the influence of the interface quality of Pt/Y3Fe5O12(111) hybrids on their spin Hall magnetoresistance. This is achieved by exposing Y3Fe5O12(111) single crystal substrates to different well-defined surface treatments prior to the Pt deposition. The quality of the Y3Fe5O12(YIG) surface, the Pt/YIG interface and the Pt layer is monitored in-situ by reflection high-energy electron diffraction and Auger electron spectroscopy as well as ex-situ by atomic force microscopy and x-ray diffraction. To identify the impact of the different surface treatments on the spin Hall magnetoresistance, angle-dependent magnetoresistance measurements are carried out at room temperature. The largest spin Hall magnetoresistance is found in Pt/YIG fabricated by a two-step surface treatment consisting of a "piranha" etch process followed by an annealing step at 500• C in pure oxygen atmosphere. Our data suggest that the small SMR in Pt/YIG without any surface treatments of the YIG substrate prior to Pt deposition is caused by a considerable carbon agglomeration at the Y3Fe5O12 surface.In the field of spintronics, the efficient generation and detection of spin currents is fundamental for new memory and logic devices. Therefore, over the past years spin current transport has been extensively studied in paramagnetic (normal) metal (NM)/ferromagnetic insulator (FMI) hybrid structures in spin pumping, spin Seebeck effect, or spin Hall magnetoresistance (SMR) experiments.1-7 In all these experiments the signal amplitude sensitively depends on the transfer of a spin current, i.e. spin angular momentum, across the NM/FMI interface and its interconversion into an electrical signal via the inverse spin Hall effect. 8,9According to theory, the relevant interface property determining the spin current flow across the NM/FMI interface is the spin mixing conductance.10,11 In several experiments it has been shown that the spin mixing conductance sensitively depends on the quality of the NM/FMI interface.12-15 For example, Jungfleisch et al. reported an increase of the spin mixing conductance by more than two orders of magnitude using a combination of piranha wet etching and an in-situ O + /Ar + plasma treatment of the FMI surface prior to the NM deposition.13 A clean and well-controlled NM/FMI interface can be obtained by in-situ deposition of the NM layer subsequent to the FMI thin film growth without breaking the vacuum. However, this procedure is often not possible if single crystal samples are used, which are superior to epitaxial thin films regarding structural and magnetic quality. In this case the NM layer is deposited ex-situ on the single crystal, which is exposed to ambient conditions prior to the deposition resulting in adsorbed molecules, mainly carbon, on the surface. As a consequence the molecules may form additional spin-scattering centers and finally provoke a loss of spin information at the NM/FMI interface.In this work we systematically investigate how different surface treatments of yttrium iron garnet (Y 3 Fe 5 O 12 , YIG) ...

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“…[6][7] Up to now, the SSE has been investigated only for a limited number of insulating ferrimagnets. Most researches focused on garnet ferrites, like YIG, due to their ultralow damping constants (in the order of 10 -4 ) and the relative high Curie temperatures of T C ~550 K. 4,5,[8][9][10][11][12][13] Current studies on YIG have revealed that the interface effects plays an important role for the detected ISHE signals. 13 The complexity of the garnet ferrites' lattice structure makes the interface termination with adjacent detection layers complicated.…”

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confidence: 99%

Thermal generation of spin current in epitaxial CoFe2O4 thin films

Guo

Herklotz

Kehlberger

et al. 2016

Applied Physics Letters

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The longitudinal spin Seebeck effect (LSSE) has been investigated in high-quality epitaxial CoFe 2 O 4 (CFO) thin films. The thermally excited spin currents in the CFO films are electrically detected in adjacent Pt layers due to the inverse spin Hall effect (ISHE). The LSSE signal exhibits a linear increase with increasing temperature gradient, yielding a LSSE coefficient of ~100 nV/K at room temperature. The temperature dependence of the LSSE is investigated from room temperature down to 30 K, showing a significant reduction at low temperatures, revealing that the total amount of thermally generated magnons decreases.Furthermore, we demonstrate that the spin Seebeck effect is an effective tool to study the magnetic anisotropy induced by epitaxial strain, especially in ultrathin films with low magnetic moments.

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Origin of the spin Seebeck effect in compensated ferrimagnets

Cited by 187 publications

References 29 publications

Antiferromagnetic Spin Seebeck Effect

Antiferromagnetic Spin Seebeck Effect

Impact of the interface quality of Pt/YIG(111) hybrids on their spin Hall magnetoresistance

Thermal generation of spin current in epitaxial CoFe2O4 thin films

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