Strong longitudinal magnetic fluctuations near critical end point in UCoAl: A 59Co-NMR study
Published Web Locationhttps://doi.org/10.1143/JPSJ.80.093707
We report 59Co-NMR measurements in UCoAl where metamagnetism occurs owing to the enhancement of ferromagnetism by a magnetic field. The metamagnetic transition from a paramagnetic (PM) state to a ferromagnetic state is a first-order transition at low temperatures, but it changes to a crossover at high temperatures on crossing the critical end point (CEP) at Tcep ∼ 12 K. The contrasting behavior between the relaxation rates 1/T 1 and 1/T2 suggests that the longitudinal magnetic fluctuation of the U moments is strongly enhanced, especially near the CEP. A wide diffusion of the fluctuation from the CEP can be confirmed even in the PM state where the magnetic transition does not occur. © 2011 The Physical Society of Japan.