Entropy 2014, 16(7), 3813-3831; doi:10.3390/e16073813
Review

Phase Competitions behind the Giant Magnetic Entropy Variation: Gd5Si2Ge2 and Tb5Si2Ge2 Case Studies

1,2,†email, 1,†email, 1,2email, 1email, 3email, 3,4email, 5email, 3email, 1,* email and 1,* email
Received: 11 April 2014; in revised form: 27 June 2014 / Accepted: 1 July 2014 / Published: 11 July 2014
(This article belongs to the Special Issue Entropy in Shape Memory Alloys)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: Magnetic materials with strong spin-lattice coupling are a powerful set of candidates for multifunctional applications because of their multiferroic, magnetocaloric (MCE), magnetostrictive and magnetoresistive effects. In these materials there is a strong competition between two states (where a state comprises an atomic and an associated magnetic structure) that leads to the occurrence of phase transitions under subtle variations of external parameters, such as temperature, magnetic field and hydrostatic pressure. In this review a general method combining detailed magnetic measurements/analysis and first principles calculations with the purpose of estimating the phase transition temperature is presented with the help of two examples (Gd5Si2Ge2 and Tb5Si2Ge2). It is demonstrated that such method is an important tool for a deeper understanding of the (de)coupled nature of each phase transition in the materials belonging to the R5(Si,Ge)4 family and most possibly can be applied to other systems. The exotic Griffiths-like phase in the framework of the R5(SixGe1-x)4 compounds is reviewed and its generalization as a requisite for strong phase competitions systems that present large magneto-responsive properties is proposed.
Keywords: entropy; phase transitions; magnetocaloric effect
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MDPI and ACS Style

Pires, A.L.; Belo, J.H.; Lopes, A.M.L.; Gomes, I.T.; Morellón, L.; Magen, C.; Algarabel, P.A.; Ibarra, M.R.; Pereira, A.M.; Araújo, J.P. Phase Competitions behind the Giant Magnetic Entropy Variation: Gd5Si2Ge2 and Tb5Si2Ge2 Case Studies. Entropy 2014, 16, 3813-3831.

AMA Style

Pires AL, Belo JH, Lopes AML, Gomes IT, Morellón L, Magen C, Algarabel PA, Ibarra MR, Pereira AM, Araújo JP. Phase Competitions behind the Giant Magnetic Entropy Variation: Gd5Si2Ge2 and Tb5Si2Ge2 Case Studies. Entropy. 2014; 16(7):3813-3831.

Chicago/Turabian Style

Pires, Ana L.; Belo, João H.; Lopes, Armandina M.L.; Gomes, Isabel T.; Morellón, Luis; Magen, Cesar; Algarabel, Pedro A.; Ibarra, Manuel R.; Pereira, André M.; Araújo, João P. 2014. "Phase Competitions behind the Giant Magnetic Entropy Variation: Gd5Si2Ge2 and Tb5Si2Ge2 Case Studies." Entropy 16, no. 7: 3813-3831.

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