Abstract
A model calculation is presented for the magnons coherent transmission and corresponding heat transport at magnetic insulating nanojunctions. The system consists of a ferromagnetically ordered ultrathin insulating junction between two semi-infinite ferromagnetically ordered leads. Spin dynamics are analyzed using the equations of motion for the spin precession displacements, valid for the range of temperatures of interest. Coherent scattering cross-sections at the junction boundary are calculated using the phase field matching theory, for all the incidence angles on the boundary from the lead bands, for arbitrary angles of incidence, at variable temperatures, and for different nano thicknesses of the ultrathin junction. The model is general; it is applied in particular to the Fe/Gd/Fe system with a sandwiched ferromagnetic Gd junction. It yields also the thermal conductivity due to the magnons coherent transmission between the two leads when these are maintained at slightly different temperatures. The calculation is carried out for state of the art values of the exchange constants, and elucidates the relation between the coherent scattering transmission of magnons and their thermal conductivity, for different thicknesses.
Highlights
Nanomaterial systems may be considered as solids for which a parameter at least varies on a scale of few nanometers up to the submicroscopic
Spin dynamics are analyzed using the equations of motion for the spin precession displacements, valid for the range of temperatures of interest
In particular we show that this nanojonction is capable of a selective transmission of magnons as a function of its thickness, which is due to the coupling between the incident propagating magnon modes of the semi-infinite Fe leads located on both sides of the nanojonction and the localized modes characteristic of the local spin dynamics at the nanojonction
Summary
Nanomaterial systems may be considered as solids for which a parameter at least varies on a scale of few nanometers up to the submicroscopic Due to their material confinement, these nanostructures present a significant atomic proportion of their material at their surfaces. EPJ Web of Conferences channel systems are provided by the models of Landauer [4], and Büttiker [5], which established a relation between the conductance of a given nanojunction and its scattering matrix In this communication, we present a model to analyze quantitatively in a first approach the coherent magnons transport via an insulating magnetic nanojonction, which may be prepared as an ultrathin film of gadolinium Gd inserted between two semi-infinite fcc leads of iron Fe. The Fe/ Fe/Gdn/Fe system is presented schematically in Fig..
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