As and Epitaxial-Growth MnSi Thin Films - OPUS Würzburg

Summary 7
bandstructure affecting the spin polarization.[Jeon 04, Li 13]
Aside from the applied field, other parameters were also changed to further characterize
the magnetization structures within the grown films. Minor loop and temperature
measurements were also performed to understand the interesting magnetization dynamics
and phases in the MnSi thin films. Minor loop measurements show the presence of
multiple magnetization states with different relaxation and saturation parameters within
the 20-nm film.[Wind 12] Temperature measurements also show features in the Hall signal
at ≈ 10K and near T c (≈ 45K), consistent with the broadened A-phase observed
in [Tono 12] for thinned MnSi plates and in [Li 13] for epitaxial films, but should be
confirmed by further measurements by other techniques.
Finally, low in-plane magnetic field characterization is also tested as a tool for probing
themagnetizationbehaviorinChapter8. Longitudinalmagnetoresistance andplanarHall
measurements are done for MnSi films. Magnetoresistance measurements show spin glasslikebehaviorforthe20-nmfilm,
whichcouldpossiblyarisefromthepresenceofbothchiral
domain types within the film.[Karh 10] Magnetoresistance measurements are unsuccessful
in detecting the effects of the different calculated uniaxial anisotropies of both films due
to shape anisotropy effects [Baue 12], but possibly show the difference between the type
of magnetic domains present within the films through low-field dependence.[Mori 85] The
planar Hall effect or PHE is shown to have an antisymmetric component with the applied
field, possibly arising from a second order Hall term (Umkehr effect), which could arise
fromspinchiralityandcrystalsymmetryinthesystemandtiedtoadditionalcontributions
to the anomalous Hall effect.[Mudu 05, Frie 06]