Fragile antiferromagnetism in the heavy-fermion compound YbBiPt

Abstract

We report results from neutron scattering experiments on single crystals of YbBiPt that demonstrate antiferromagnetic order characterized by a propagation vector, ${\mathbit{\ensuremath{\tau}}}_{\mathrm{AFM}}$ = ($\frac{1}{2}\frac{1}{2}\frac{1}{2}$), and ordered moments that align along the [1 1 1] direction of the cubic unit cell. We describe the scattering in terms of a two-Gaussian peak fit, which consists of a narrower component that appears below ${T}_{\mathrm{N}}\ensuremath{\approx}0.4$ K and corresponds to a magnetic correlation length of ${\ensuremath{\xi}}_{\mathrm{n}}\ensuremath{\approx}$ 80 $\AA{}$, and a broad component that persists up to ${T}^{*}\ensuremath{\approx}$ 0.7 K and corresponds to antiferromagnetic correlations extending over ${\ensuremath{\xi}}_{\mathrm{b}}\ensuremath{\approx}$ 20 $\AA{}$. Our results illustrate the fragile magnetic order present in YbBiPt and provide a path forward for microscopic investigations of the ground states and fluctuations associated with the purported quantum critical point in this heavy-fermion compound.