Magnetotransport properties of Fe doped MnSi under pressure

In an exotic magnetic phase known as a skyrmion lattice, the coupling between spin texture and conduction electrons produces enormous emergent magnetic fields, experimentally detectable with electrical transport measurements as evidenced in MnSi and similar B20 structured magnets. We present magnetotrasport data from a helimagnet Mn$_1-x$Fe$x$Si ($x$ = 0.09) under hydrostatic pressure. In this system, both pressure and Fe doping suppress long-range magnetic order while their effects on the saturated magnetic moment and helical pitch length are quite different. We discuss the size and characteristics of the topological Hall effect, a signature of these emergent magnetic fields, in pure and 9\% Fe doped MnSi under pressure, and compare to other samples with different Fe compositions at ambient pressure.