Barkhausen effect
= Barkhausen effect
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= Barkhausen noise
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The <Barkhausen effect> consists of abrupt <magnetization> changes during a smooth applied <magnetic field> sweep. Its inductive <signal> is <Barkhausen noise>, often arising from collective <magnetic domain wall> motion.<The Barkhausen effect by Gianfranco Durin and Stefano Zapperi>[§I, p. 2: wall-motion interpretation]{ref}
The distinction is between a smooth drive and an intermittent material response. A smooth macroscopic <hysteresis> curve can hide smaller jumps. By <Faraday's law of induction>, a <pickup coil> responds to the rate of change of linked <magnetic flux>, so a rapid jump can be conspicuous even when the total change is small. A pulse is not one <chemical atom> flipping: neither its height nor the number of audible clicks counts individual <Electron> <spins>. Qualitative crackling alone does not establish quantum <spin>; collective switching also admits a classical model with trapped interfaces. Compare the distinct mechanical readout of <angular momentum> transfer in the <Einstein-de Haas effect>.