Superconductivity and non-Fermi liquid behavior on the border of itinerant ferromagnetism

When magnetic order is suppressed under pressure, a superconducting (SC) phase emerges in the ferromagnet UGe₂ and an extended non-Fermi liquid (NFL) regime is observed in the helimagnet MnSi. We report thermal expansion measurements of UGe₂ under pressure by means of neutron Larmor diffraction. We find a new, putatively non-magnetic transition at the temperature TL at pressures close to the SC phase. In MnSi we report Hall effect measurements under pressure. We find a topological Hall effect, as the signature of a topologically non-trivial spin texture, above the critical pressure in the NFL regime.