Quantum criticality in the frustrated Laves phase compound [formula omitted

Abstract

Geometric frustration in nearly magnetic metals provides a promising and relatively little explored path to obtaining high electronic densities of states—the hatching condition of novel quantum order. Various geometrically frustrated compounds close to the border of magnetism can be found amongst the intermetallic C14 and C15 Laves phases and we have selected NbFe 2 as one of the more interesting examples. We report on measurements of the DC magnetisation, AC magnetic susceptibility, specific heat capacity and electrical resistivity in off-stoichiometric Nb 1 - y Fe 2 + y ( y ≃ - 0.04 ). Our sample is classified as a strongly enhanced Pauli paramagnet with anomalous resistivity power-law behaviour: the low-temperature electrical resistivity follows the form ρ = ρ 0 + AT α with 1 < α < 1.5 over a wide range and returns to the quadratic temperature dependence expected from Fermi Liquid theory in its simplest form only below 500 mK. The absolute magnitude of the measured low-temperature heat capacity is inconsistent with a model based solely on proximity to ferromagnetism and suggests a significant contribution from antiferromagnetic fluctuations.