Publication: Colossal heating efficiency via eddy currents in amorphous microwires with nearly zero magnetostriction
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2020-01-17
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Nature Publishing group
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Abstract
It is well stablished that heating efficiency of magnetic nanoparticles under radiofrequency fields is due to the hysteresis power losses. In the case of microwires (MWs), it is not clear at all since they undergo non-coherent reversal mechanisms that decrease the coercive field and, consequently, the heating efficiency should be much smaller than the nanoparticles. However, colossal heating efficiency has been observed in MWs with values ranging from 1000 to 2800W/g, depending on length and number of microwires, at field as low as H = 36 Oe at f = 625 kHz. It is inferred that this colossal heating is due to the Joule effect originated by the eddy currents induced by the induction field B = M + chi H parallel to longitudinal axis. This effect is observed in MWs with nearly zero magnetostrictive constant as Fe_ (2.25)Co_(72.75)Si_(10)B_(15) of 30 mu m magnetic diameter and 5 mm length, a length for which the inner core domain of the MWs becomes axial. This colossal heating is reached with only 24 W of power supplied making these MWs very promising for inductive heating applications at a very low energy cost.
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©2020 Nature Publishing group
This work was supported by grants from the Spanish Ministry of Science and Innovation RTI2018-095856-B-C21 and Comunidad de Madrid NANOMAGCOST S2018/NMT-4321. The authors also acknowledge the technical support given by Fernando Giacomone financed by Spanish Ministery of Science and Innovation, PTA2015-10497-I.