Unusual Hall Effect Anomaly in MnSi
Minhyea Lee, University
of Colorado
The interplay
between spin and charge of electrons in solids provides a rich setting
for exploring collective behavior of many interacting quantum-mechanical
particles. Since its discovery more than century ago, the Hall effect
remains one of the most fundamental probes of spin-charge coupling. In a simple
metal, the Hall effect arises from the deflection of electrons in the applied magnetic
field, and is related to the density of carriers. In ferromagnets, the
spontaneous magnetization contributes to an additional Hall current and gives
rise to the so-called anomalous Hall effect. MnSi is remarkably free of
impurities with a low Curie temperature and thus provides an excellent testing
ground for theories of the anomalous Hall effect, not to mention the recent
exciting discovery of the partial-order state at high pressure. In this talk, I
present a distinct, unexpected additional contribution to the Hall effect in
MnSi, which has not been observed before in helical magnetic systems. I will
discuss the evidence favoring the existence of non-trivial spin texture, i.e.
non-zero chirality, for the origin of the anomaly.