  The evolution of the magnetic and charge transport properties of itinerant
magnetic metal MnSi with the substitution of Al and Ga on the Si site is
investigated. We observe an increase in unit cell volume indicating that both
Al and Ga substitutions create negative chemical pressure. There are
substantial increases in the Curie temperature and the ordered moment
demonstrating that the substitutions give the magnetism a more local character.
The substitutions also increase the range of temperature and field where the
skyrmion phase is stable due to a change in the character of the magnetism. In
contrast to the behavior of pure MnSi and expectations for the intrinsic
anomalous Hall effect, we find a significant temperature dependence to the
magnitude and sign of anomalous Hall conductivity constant in Al or Ga
substituted samples. This temperature dependence likely reflects changes in the
spin-orbit coupling strength with temperature, which may have significant
consequences on the helical and skyrmion states. Overall, we observe a
continuous evolution of magnetic and charge transport properties through
positive to negative pressure
