Magneto-dynamic properties of thin films and interfaces
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- Institutt for fysikk 
Magnonics is a developing branch in the field of condensed matter physics with the potential to fulfill the future demand for miniaturized, fast, and energy-efficient spintronics devices. This thesis explores both a novel magnetodynamic system— the interface states in oxide system, as well as the tunability of dynamic properties due to nanostructuring in one-dimensional magnonic crystals (1D MCs). It also introduces a novel approach to propagating spin-wave spectroscopy that allows for higher sensitivity in characterization of low-damped materials. The magnetodynamic properties of an induced magnetic state at complex oxide—La0.7Sr0.3MnO3/SrTiO3(LSMO/STO)(111)—heterostructure interface is investigated employing Ferromagnetic Resonance (FMR) spectroscopy. This study details the important characteristics of interface mode at LSMO/STO (111) interface. The study also discuss the complex structural or electronic and orbital reconstructions which could give rise to such interface magnetic state. The investigation done on the magnetodynamic properties of dipole coupled 1D MCs explore the possibility to use dipolar coupling to tailor the static and magnetodynamic properties of MCs. The magnetodynamic properties have been investigated by two complementary FMR spectroscopies in combination with micromagnetic simulations and analytical calculations. The impact of dipolar coupling on the magnetodynamic damping is also presented. An extension of the propagating spin-wave spectroscopy to a more sensitive field-sweep protocol is detailed. To this end the spin-wave propagation parameters investigated in Permalloy (NiFe) by two different excitation source—voltage pulse and continuous microwave have been investigated and compared. It is found that the continuous wave excitation allows for higher sensitivity measurements of a spin-wave mode in thinner films. This method has been used to investigate spin-wave propagation properties in half-metallic—Co2FeAl Heusler alloy thin films.
Has partsPaper 1: Singh, Suraj Kumar; Bolstad, Torstein; Hallsteinsen, Ingrid; Tybell, Per Thomas Martin; Wahlström, Erik. Magneto-dynamic properties of complex oxide—La0.7Sr0.3MnO3/SrTiO3— heterostructure interface. Applied Physics Letters 2019 ;Volum 114.(22) https://doi.org/10.1063/1.5093324
Paper 2: Singh, S.; Wang, X.; Kumar, A.; Qaiumzadeh, A.; Svedlindh, P.; Tybell, T.; Whatström, E. Mapping the dipolar coupling and magnetodynamic properties of dipole coupled 1D magnonic crystals.
Paper 3: Singh, S.; Furtula,V.; Tybell, T.; Whatström, E. Pulse versus continuous wave characterization of propagating spin waves in thin magnetic films.
Paper 4: Singh, S.; Gupta, N.K.; Hait,S.; Chaudhary, S.; Tybell, T.; Whatström, E. Propagation properties of spin wave in Co2FeAl, half-metallic Heusler alloy, ultrathin film.