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Published July 1, 2015 | Published + Submitted
Journal Article Open

Barkhausen noise in the random field Ising magnet Nd_2Fe_(14)B

Abstract

With sintered needles aligned and a magnetic field applied transverse to its easy axis, the rare-earth ferromagnet Nd_2Fe_(14)B becomes a room-temperature realization of the random field Ising model. The transverse field tunes the pinning potential of the magnetic domains in a continuous fashion. We study the magnetic domain reversal and avalanche dynamics between liquid helium and room temperatures at a series of transverse fields using a Barkhausen noise technique. The avalanche size and energy distributions follow power-law behavior with a cutoff dependent on the pinning strength dialed in by the transverse field, consistent with theoretical predictions for Barkhausen avalanches in disordered materials. A scaling analysis reveals two regimes of behavior: one at low temperature and high transverse field, where the dynamics are governed by the randomness, and the second at high temperature and low transverse field, where thermal fluctuations dominate the dynamics.

Additional Information

©2015 American Physical Society. (Received 2 February 2015; published 23 July 2015) Work at the University of Chicago was supported by the Department of Energy Office of Basic Energy Sciences, Grant No. DE-FG02-99ER45789.

Attached Files

Published - PhysRevB.92.024424.pdf

Submitted - 1502.04234.pdf

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