Itinerant Ferromagnetism and Quantum Criticality in Sc$_3$In

The electronic structure and magnetic properties of hexagonal Sc$_3$In are calculated within density functional theory. We find that the Fermi energy lies in a region of flat Sc $d$ derived bands leading to a peak in the density of states and Stoner ferromagnetism. The calculated local spin density and generalized gradient approximation spin magnetizations are both enhanced with respect to experiment, which is an indication of significant quantum critical fluctuations, neglected in these approximations. We find, as expected, that the ferromagnetism is initially enhanced under pressure, meaning that the critical point cannot be reached with modest pressure. However, we find that the density of states peak around the Fermi energy and the calculated density functional magnetic properties are sensitive to the $c/a$ ratio, so that the quantum critical point may be reached under uniaxial strain.