We report ^59Co-NMR measurements in UCoAl where a metamagnetism occurs due to enhancement of ferromagnetism by 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 pint (CEP) at T_CEP ~ 12 K. The contrasting behavior between the relaxation rates 1/T_1 and 1/T_2 suggests that the longitudinal magnetic fluctuation of U moment 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.
@article{arxiv.1107.5224,
title = {Strong Longitudinal Magnetic Fluctuations near Critical End Point in UCoAl: A ^59Co-NMR Study},
author = {Hiroki Nohara and Hisashi Kotegawa and Hideki Tou and Tatsuma D. Matsuda and Etsuji Yamamoto and Yoshinori Haga and Zachary Fisk and Yoshichika Onuki and Dai Aoki and Jacques Flouquet},
journal= {arXiv preprint arXiv:1107.5224},
year = {2015}
}
Comments
5pages, 6 figures, to be published in J. Phys. Soc. Jpn