Magnetic transition and spin fluctuations in the unconventional antiferromagnetic compoundYb3Pt4

Abstract

Muon spin rotation and relaxation measurements have been carried out on the unconventional antiferromagnetYb3Pt4. Oscillations areobserved below TN = 2.22(1) K, consistent with the antiferromagnetic (AFM) Néel temperature observed in bulkexperiments. In agreement with neutron diffraction experiments the oscillation frequencyωμ(T)/2π followsan S = 1/2 mean-field temperature dependence, yielding a quasistatic local field of 1.71(2) kOe atT = 0. A crude estimate gives an ordered moment of ∼ 0.66 μB atT = 0, comparableto 0.81 μB from neutron diffraction. As from above the dynamic relaxation rateλd exhibits no critical slowing down, consistent with a mean-field transition. In the AFM phase aT-linearfit to λd(T), appropriate to a Fermi liquid, yields highly enhanced values ofλd/T and the Korringaconstant Kμ2T/λd, with Kμ the estimated muon Knight shift. A strong suppression ofλd by applied field is observed in the AFM phase. These properties are consistentwith the observed large Sommerfeld–Wilson and Kadowaki–Woods ratios inYb3Pt4 (although the data do not discriminate between Fermi-liquidand non-Fermi-liquid states), and suggest strong enhancement ofq≈0 spin correlations between large-Fermi-volume band quasiparticles in the AFM phase ofYb3Pt4.