Giant Hall effect in Ni-Mn-In Heusler alloys

We present experimental results on the giant Hall effect in the Heusler alloy ${\text{Ni}}_{50}{\text{Mn}}_{50\ensuremath{-}\text{x}}{\text{In}}_{\text{x}}$ with $x=15.2$. An unusual field dependence of the Hall resistivity $({\ensuremath{\rho}}_{H})$ was observed in the vicinity of the martensitic phase transition, where ${\ensuremath{\rho}}_{H}$ sharply increases up to ${\ensuremath{\rho}}_{H}$ $(15\text{ }\text{kOe})=50\text{ }\ensuremath{\mu}\ensuremath{\Omega}\text{ }\text{cm}$. This value is comparable with the giant Hall resistivity in magnetic nanogranular alloys. Associated with ${\ensuremath{\rho}}_{H}$, the Hall angle reaches a giant value of ${\text{tan}}^{\ensuremath{-}1}\text{ }0.5$. An explanation of the giant Hall effect in ${\text{Ni}}_{50}{\text{Mn}}_{50\ensuremath{-}\text{x}}{\text{In}}_{\text{x}}$ Heusler alloys has been suggested.