title: Origin of the spin Seebeck effect in compensated ferrimagnets.
abstract: Magnons are the elementary excitations of a magnetically ordered system. In ferromagnets, only a single band of low-energy magnons needs to be considered, but in ferrimagnets the situation is more complex owing to different magnetic sublattices involved. In this case, low lying optical modes exist that can affect the dynamical response. Here we show that the spin Seebeck effect (SSE) is sensitive to the complexities of the magnon spectrum. The SSE is caused by thermally excited spin dynamics that are converted to a voltage by the inverse spin Hall effect at the interface to a heavy metal contact. By investigating the temperature dependence of the SSE in the ferrimagnet gadolinium iron garnet, with a magnetic compensation point near room temperature, we demonstrate that higher-energy exchange magnons play a key role in the SSE.
authors: Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany.
authors: Stephan
authors: S
authors: Geprägs
authors: Institute of Physics, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany.|Materials Science in Mainz, Staudinger Weg 9, 55128 Mainz, Germany.
authors: Andreas
authors: A
authors: Kehlberger
authors: Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany.|Physik-Department, Technische Universität München, 85748 Garching, Germany.
authors: Francesco Della
authors: FD
authors: Coletta
authors: WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.|ERATO, Japan Science and Technology Agency, Sendai 980-8577, Japan.
authors: Zhiyong
authors: Z
authors: Qiu
authors: Institute of Physics, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany.
authors: Er-Jia
authors: EJ
authors: Guo
authors: Institute of Physics, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany.
authors: Tomek
authors: T
authors: Schulz
authors: Institute of Physics, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany.|Materials Science in Mainz, Staudinger Weg 9, 55128 Mainz, Germany.
authors: Christian
authors: C
authors: Mix
authors: Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany.|Physik-Department, Technische Universität München, 85748 Garching, Germany.
authors: Sibylle
authors: S
authors: Meyer
authors: Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany.|Kavli Institute of NanoScience, Delft University of Technology, 2628 Delft, The Netherlands.
authors: Akashdeep
authors: A
authors: Kamra
authors: Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany.
authors: Matthias
authors: M
authors: Althammer
authors: Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany.|Nanosystems Initiative Munich (NIM), Schellingstraße 4, 80799 München, Germany.
authors: Hans
authors: H
authors: Huebl
authors: Institute of Physics, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany.|Materials Science in Mainz, Staudinger Weg 9, 55128 Mainz, Germany.
authors: Gerhard
authors: G
authors: Jakob
authors: Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.|Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan.
authors: Yuichi
authors: Y
authors: Ohnuma
authors: ERATO, Japan Science and Technology Agency, Sendai 980-8577, Japan.|Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan.
authors: Hiroto
authors: http://orcid.org/0000-0002-6844-6477
authors: H
authors: Adachi
authors: Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
authors: Joseph
authors: J
authors: Barker
authors: ERATO, Japan Science and Technology Agency, Sendai 980-8577, Japan.|Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan.
authors: Sadamichi
authors: S
authors: Maekawa
authors: WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.|Kavli Institute of NanoScience, Delft University of Technology, 2628 Delft, The Netherlands.|Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
authors: Gerrit E W
authors: http://orcid.org/0000-0002-3615-8673
authors: GEW
authors: Bauer
authors: WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.|Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.|Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan.|CREST, Japan Science and Technology Agency, Tokyo 102-0076, Japan.
authors: Eiji
authors: E
authors: Saitoh
authors: Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany.|Physik-Department, Technische Universität München, 85748 Garching, Germany.|Nanosystems Initiative Munich (NIM), Schellingstraße 4, 80799 München, Germany.
authors: Rudolf
authors: R
authors: Gross
authors: Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany.|Nanosystems Initiative Munich (NIM), Schellingstraße 4, 80799 München, Germany.
authors: Sebastian T B
authors: STB
authors: Goennenwein
authors: Institute of Physics, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany.|Materials Science in Mainz, Staudinger Weg 9, 55128 Mainz, Germany.
authors: Mathias
authors: M
authors: Kläui