Effective exchange interaction for terahertz spin waves in iron layers

The exchange stiffness is a central material parameter of all ferromagnetic materials. Its value controls the Curie temperature as well as the dynamic properties of spin waves to a large extend. Using ultrashort spin current pulses we excite perpendicular standing spin waves (PSSW) in ultrathin epit...

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Bibliographic Details
Published inarXiv.org
Main Authors Brandt, Liane, Ritzmann, Ulrike, Liebing, Niklas, Ribow, Mirko, Razdolski, Ilya, Brouwer, Piet, Melnikov, Alexey, Woltersdorf, Georg
Format Paper
LanguageEnglish
Published Ithaca Cornell University Library, arXiv.org 02.06.2021
Subjects
Curie temperature
Current pulses
Exchanging
Ferromagnetic materials
Iron
Magnetism
Magnons
Reduction
Spin dynamics
Spintronics
Stiffness
Thickness
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Summary:The exchange stiffness is a central material parameter of all ferromagnetic materials. Its value controls the Curie temperature as well as the dynamic properties of spin waves to a large extend. Using ultrashort spin current pulses we excite perpendicular standing spin waves (PSSW) in ultrathin epitaxial iron layers at frequencies of up to 2.4 THz. Our analysis shows that for the PSSWs the observed exchange stiffness of iron is about 20% smaller compared to the established iron bulk value. In addition, we find an interface-related reduction of the effective exchange stiffness for layers with the thickness below 10 nm. To understand and discuss the possible mechanisms of the exchange stiffness reduction we develop an analytical 1D-model. In doing so we find that the interface induced reduction of the exchange stiffness is mode-dependent.
ISSN:2331-8422