Spin Susceptibility of CeOs₄Sb₁₂Probed by¹²¹Sb-NMR

Abstract

We performed an 121 Sb-NMR measurement on CeOs 4 Sb 12 . The temperature (T ) dependence of its Knight shift was studied in detail by using an aligned powdered sample and two sets of NQR parameters. A c-f hybridization gap model with the same gap magnitude as that obtained by considering the nuclear spin-lattice relaxation rate 1/T 1 cannot explain the Knight shift above ∼ 70 K. This may be because of the existence of q-dependent spin fluctuations. The increase in the Knight shift with decreasing temperatures below ∼ 70 K revealed a ferromagnetic correlation. This result and previous 1/T 1 measurements indicate the presence of both ferromagnetic and antiferromagnetic fluctuations that may be related to an anomalous ordered phase in CeOs 4 Sb 12