Study of Correlation between Charge-density-wave and Magnetism in UPt₂Si₂ using Polarized Neutron Scattering

Abstract

We examined the antiferromagnetic (AFM) structure of UPt₂Si₂, which develops below T_N = 34 K, using polarized and unpolarized neutron diffraction techniques. Previous studies report that this system undergoes the AFM order with the propagation vector Q = 0 and magnetic moments aligned along the c-axis. Notably, our recent resonant X-ray scattering (RXS) experiments revealed that this magnetic structure is modulated by the charge-density-wave (CDW) order, which is formed in one of the Pt layers with the propagation vector q_CDW = (∼0.42, 0, 0) below ∼320 K. In this neutron scattering study, we observed the magnetic scattering contributions below T_N at the superlattice reflections corresponding to q_CDW. Our detailed analysis confirmed the presence of the transversal magnetic modulation in the AFM phase and quantified its amplitude to be 0.72(2) μ_B/U. These results indicate that the CDW causes the ordered magnetic moments to tilt by up to ～20° in the AFM phase, suggesting significant hybridization between the U 5f and Pt 5d electrons in this compound.