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Nucleation and dynamics of the metamagnetic transition in magnetocaloric La(Fe,Mn,Si)(13)

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Title: Nucleation and dynamics of the metamagnetic transition in magnetocaloric La(Fe,Mn,Si)(13)
Authors: Lovell, E
Bratko, M
Caplin, AD
Cohen, LF
Item Type: Journal Article
Abstract: Refrigeration cycle rates of the order of 15 Hz are desirable for efficient solid state based magnetocaloric cooling, placing an upper bound on the combined magnetic transition and the heat transfer times of the order of tens of msecs. We use microcalorimetry and magnetometry to probe the transition dynamics as a function of magnetic field sweep-rate, sample size, thermal environment, temperature and hydrostatic pressure in LaFe11.74Mn0.06Si1.20. Although second order caloric materials follow the magnetisation or demagnetisation driving field without lag, here we show that the field driven evolution of the first-order phase transition in La(Fe,Si)13-based compounds show temporal dynamics on timescales that are significantly longer than tens of msecs, associated with the thermal linkage within the sample and the linkage to the external bath. We observe that features associated with the first nucleation of the transition are field sweep rate independent, and from measurements of the latent heat we infer that the barriers to magnetisation and demagnetisation are of different magnitude. Increasing the temperature or applying hydrostatic pressure reduces the dynamic effects, suggestive of diminishing first-order character of the transition under these conditions.
Issue Date: 25-Oct-2017
Date of Acceptance: 30-Aug-2017
URI: http://hdl.handle.net/10044/1/55235
DOI: https://dx.doi.org/10.1088/1361-6463/aa893e
ISSN: 0022-3727
Publisher: IOP Publishing
Journal / Book Title: Journal of Physics D: Applied Physics
Volume: 50
Issue: 42
Copyright Statement: ©2017 IOP Publishing Ltd.
Keywords: Science & Technology
Physical Sciences
Physics, Applied
magnetic transition
latent heat
02 Physical Sciences
09 Engineering
Applied Physics
Publication Status: Published
Article Number: 424004
Appears in Collections:Physics
Experimental Solid State
Faculty of Natural Sciences