Berlin 2018 – scientific programme

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MA: Fachverband Magnetismus

MA 20: Magnetocaloric effects (joint session MA/TT)

MA 20.1: Talk

Tuesday, March 13, 2018, 09:30–09:45, EB 407

A DFT and Monte Carlo approach to simulating the magnetocaloric effect in magnetovolume-coupled materials — •Nuno Fortunato^1,2, João Amaral², Gercsi Zsolt³, João Gonçalves², Vitor Amaral², Hongbin Zhang¹, Oliver Gutfleisch¹, Vitalij Pecharsky⁴, Karl Sandeman⁵, and Lesley Cohen⁵ — ¹TU Darmstadt, Germany — ²CICECO, Universidade de Aveiro, Portugal — ³Physics, Trinity College Dublin, Ireland — ⁴Ames Laboratory, United States — ⁵Department of Physics, Imperial College London, United Kingdom

Magnetic refrigeration is an emergent technology promising for eco-friendly and more energy efficient refrigeration applications, using the magnetocaloric effect (MCE). Magnetovolume effects contribute significantly to the MCE, however the estimation of MCE with magnetovolume effects remains a challenge. In this work, we simulate the MCE using a microscopic model solved by Monte Carlo methods that evaluate the thermodynamic density of states. The magnetic interaction (J_ij) between local moments is considered a function of volume (v), together with external field (H) and lattice volume terms: H = −1/2Σ J_ij(v) S_i.S_j + 1/2Kv² −HM, where K is compressibility.

Simulation results are compared with the experimental data of Gd, the typical benchmark material for room-temperature magnetic cooling applications. We show that such a simple model quantitatively reproduces experimental data for the MCE and the magnetostriction. This work paves the way to a ’ground-up’, fast computational approach to optimize and search for magnetic refrigerant materials.