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arXiv · 1107.5224

Strong Longitudinal Magnetic Fluctuations near Critical End Point in UCoAl: A ^59Co-NMR Study

Hiroki Nohara·Hisashi Kotegawa·Hideki Tou·Tatsuma D. Matsuda·Etsuji Yamamoto·Yoshinori Haga·Zachary Fisk·Yoshichika Onuki·Dai Aoki·Jacques Flouquet
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Abstract

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.

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Hiroki Nohara, Hisashi Kotegawa, Hideki Tou, Tatsuma D. Matsuda, Etsuji Yamamoto, Yoshinori Haga, Zachary Fisk, Yoshichika Onuki, Dai Aoki, Jacques Flouquet. 2011-07-26. Strong Longitudinal Magnetic Fluctuations near Critical End Point in UCoAl: A ^59Co-NMR Study. https://doi.org/10.1143/jpsj.80.093707

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