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Caloric effects around phase transitions in magnetic materials described by ab initio theory : the electronic glue and fluctuating local moments
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Mendive-Tapia, Eduardo and Staunton, Julie B. (2020) Caloric effects around phase transitions in magnetic materials described by ab initio theory : the electronic glue and fluctuating local moments. Journal of Applied Physics, 127 (11). 113903. doi:10.1063/5.0003243
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Official URL: http://dx.doi.org/10.1063/5.0003243
Abstract
We describe magneto-, baro-, and elastocaloric effects (MCEs, BCEs, and eCEs) in materials, which possess both discontinuous (first-order) and continuous (second-order) magnetic phase transitions. Our ab initio theory of the interacting electrons of materials in terms of disordered local moments has produced explicit mechanisms for the drivers of these transitions, and here, we study associated caloric effects in three case studies where both types of transition are evident. Our earlier work had described FeRh’s magnetic phase diagram and large MCE. Here, we present calculations of its substantial BCE and eCE. We describe the MCE of dysprosium and find very good agreement with experimental values for isothermal entropy ((ΔSiso) and adiabatic temperature (ΔTad) changes over a large temperature span and different applied magnetic field values. We examine the conditions for optimal values of both ΔSiso and ΔTad that comply with a Clausius–Clapeyron analysis, which we use to propose a promising elastocaloric cooling cycle arising from the unusual dependence of the entropy on temperature and biaxial strain found in our third case study—the Mn3GaN antiperovskite. We explain how both ΔSiso and ΔTad can be kept large by exploiting the complex tensile strain–temperature magnetic phase diagram, which we had earlier predicted for this material and also propose that hysteresis effects will be absent from half of the caloric cycle. This rich and complex behavior stems from the frustrated nature of the interactions among the Mn local moments.
| Item Type: | Journal Article | ||||||||||||
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| Subjects: | Q Science > QC Physics | ||||||||||||
| Divisions: | Faculty of Science > Physics | ||||||||||||
| Library of Congress Subject Headings (LCSH): | Magnetic materials , Cooling curves | ||||||||||||
| Journal or Publication Title: | Journal of Applied Physics | ||||||||||||
| Publisher: | American Institute of Physics | ||||||||||||
| ISSN: | 0021-8979 | ||||||||||||
| Official Date: | 18 March 2020 | ||||||||||||
| Dates: |
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| Volume: | 127 | ||||||||||||
| Number: | 11 | ||||||||||||
| Article Number: | 113903 | ||||||||||||
| DOI: | 10.1063/5.0003243 | ||||||||||||
| Status: | Peer Reviewed | ||||||||||||
| Publication Status: | Published | ||||||||||||
| Publisher Statement: | “This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in J. Appl. Phys. 127, 113903 (2020); https://doi.org/10.1063/5.0003243 and may be found at http://dx.doi.org/10.1063/5.0003243 | ||||||||||||
| Access rights to Published version: | Restricted or Subscription Access | ||||||||||||
| RIOXX Funder/Project Grant: |
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