Dynamical magnetic correlations in the Kondo insulator YbB₁₂

Abstract

Positive muon spectroscopy (μSR) and 170Yb Mössbauer absorption measurements have been performed in the cubic Kondo insulator YbB12 down to the 50 mK temperature range. We observe a paramagnetic fluctuation mode at low temperature, with a weak moment amplitude ( ≈ 10−2 μB) and a slow fluctuation frequency ( ≈ 60 MHz) which remains constant between 0.04 K and 4.2 K. No indication of a magnetic phase transition is found down to 0.04 K.