Abstract
Through the use of the Monte Carlo simulations utilising the mean-field approach, we show that a dense assembly of separated ultra-small magnetic nanoparticles embedded into a non-magnetic deformable matrix can be characterized by a large isothermal magnetic entropy change even upon applying a weak magnetic field with values much smaller than one Tesla. We also show that such entropy change may be very significant in the vicinity of the room temperature which effect normally requires an application of a strong external magnetic field. The deformable matrix chosen in this work as a host for magnetic nanoparticles adopts a thin film form with a large surface area to volume ratio. This in turn in combination with a strong magneto-volume coupling exhibited by this material allows us to show its suitability to be used in the case of a variety of applications utilising local cooling/heating such as future magnetic refrigerants.
Highlights
Through the use of the Monte Carlo simulations utilising the mean-field approach, we show that a dense assembly of separated ultra-small magnetic nanoparticles embedded into a non-magnetic deformable matrix can be characterized by a large isothermal magnetic entropy change even upon applying a weak magnetic field with values much smaller than one Tesla
The approach associated with the ferromagnet-paramagnet phase transition within the room temperature range ensures a large change in the value of the isothermal magnetic entropy ΔS at room temperature (MCE usually is described either by the isothermal entropy change ΔS or the adiabatic temperature change ΔT)
We investigate the effect that different factors such as the change in the geometric configuration assumed by the considered system and the variation in the external magnetic field has on the extent of the magnetocaloric effect (MCE) which in this case corresponds to the variation in the isothermal magnetic entropy ΔS
Summary
Through the use of the Monte Carlo simulations utilising the mean-field approach, we show that a dense assembly of separated ultra-small magnetic nanoparticles embedded into a non-magnetic deformable matrix can be characterized by a large isothermal magnetic entropy change even upon applying a weak magnetic field with values much smaller than one Tesla. The deformable matrix chosen in this work as a host for magnetic nanoparticles adopts a thin film form with a large surface area to volume ratio This in turn in combination with a strong magneto-volume coupling exhibited by this material allows us to show its suitability to be used in the case of a variety of applications utilising local cooling/heating such as future magnetic refrigerants. Upon being inspired by this work, in the following years, many researchers made an attempt to identify other ferromagnetic materials that are capable of exhibiting a large MCE at room temperature Such studies were focused primarily on adjusting the thermodynamic parameters of tested materials in a way so that the critical temperature Tc at which the ferromagnet-paramagnet phase transition takes place would be within the room temperature range. We analyse its capability to exhibit this effect without the presence of a strong external magnetic field in order to assess its suitability to be used in the case of applications requiring local magnetic cooling
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