English
 
User Manual Privacy Policy Disclaimer Contact us
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT

Released

Journal Article

Caloric effects around phase transitions in magnetic materials described by ab initio theory: The electronic glue and fluctuating local moments

MPS-Authors
/persons/resource/persons249147

Mendive-Tapia,  Eduardo
Computational Phase Studies, Computational Materials Design, Max-Planck-Institut für Eisenforschung GmbH, Max Planck Society;
Department of Physics, University of Warwick, Coventry, CV4 7AL, UK;

External Ressource
No external resources are shared
Fulltext (public)
There are no public fulltexts stored in PuRe
Supplementary Material (public)
There is no public supplementary material available
Citation

Mendive-Tapia, E., & Staunton, J. 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.


Cite as: http://hdl.handle.net/21.11116/0000-0006-B9AC-8
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 (Δ S i s o) and adiabatic temperature (Δ T a d) changes over a large temperature span and different applied magnetic field values. We examine the conditions for optimal values of both Δ S i s o and Δ T a d 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 Mn 3GaN antiperovskite. We explain how both Δ S i s o and Δ T a d 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. © 2020 Author(s).