Abstract
We studied the transient behavior of the spin current generated by the longitudinal spin Seebeck effect (LSSE) in a set of platinum-coated yttrium iron garnet (YIG) films of different thicknesses. The LSSE was induced by means of pulsed microwave heating of the Pt layer and the spin currents were measured electrically using the inverse spin Hall effect in the same layer. We demonstrate that the time evolution of the LSSE is determined by the evolution of the thermal gradient triggering the flux of thermal magnons in the vicinity of the YIG/Pt interface. These magnons move ballistically within the YIG film with a constant group velocity, while their number decays exponentially within an effective propagation length. The ballistic flight of the magnons with energies above 20K is a result of their almost linear dispersion law, similar to that of acoustic phonons. By fitting the time-dependent LSSE signal for different film thicknesses varying by almost an order of magnitude, we found that the effective propagation length is practically independent of the YIG film thickness. We consider this fact as strong support of a ballistic transport scenario - the ballistic propagation of quasi-acoustic magnons in room temperature YIG.
Original language | English |
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Article number | 234003 |
Number of pages | 7 |
Journal | Journal Physics D: Applied Physics |
Volume | 51 |
Issue number | 23 |
DOIs | |
Publication status | Published - 13 Jun 2018 |
Bibliographical note
Financial support by Deutsche Forschungsgemeinschaft (DFG) within Priority Program 1538 'Spin Caloric Transport' (project SE 1771/4-2) and DFG project INST 248/178-1 as well as technical support from the Nano Structuring Center, TU Kaiserslautern are gratefully acknowledged.All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Acoustics and Ultrasonics