Thermopower and electrical resistivity behavior near the martensitic transition in Gd-5(SixGe1-x)(4) magnetocaloric compounds

• Tipo: Artigo em Livro de Atas de Conferência Internacional
• Data: 2005

Autores

Pinto, Ryan P. (Autor) Outra; Sousa, João Bessa (Autor) FCUP; Correia, Francisco C. (Autor) Outra; Araújo, João Pedro (Autor) FCUP; Braga, Melissa E. (Autor) Outra; Pereira, André M. (Autor) FCUP; Morellón, Luis (Autor) Outra; Algarabel, Pedro A. (Autor) Outra; Magén, César (Autor) Outra; Ibarra, Manuel Ricardo (Autor) Outra

Ata de Conferência Internacional

Título: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

Páginas: 661-664

2nd Joint European Magnetic Symposia (JEMS 04)

Dresden, GERMANY, SEP 05-10, 2004

Indexação

ISI Web of Knowledge - 9 Citações

Scopus - 9 Citações

Outras Informações

ID Authenticus: P-000-425

DOI: 10.1016/j.jmmm.2004.11.331

Abstract (EN): Recently, the Gd-5(SixGe1-x)(4) system exhibits fascinating physical properties, namely giant magnetocaloric, magnetoresistance and magnetostriction effects near a first-order (martensitic like; T = T-S) magneto-structural transition. We report the thermopower behavior S(T) between 10 and 300 K for compounds with x = 0, 0.10 and 0.45, belonging to three distinct regions of the magnetic/structural phase diagram. Large thermopower changes are observed near T-S for X = 0.10 (T-S = 78 K; AFM-Orthorhombic II/FM-Ortho.I) and for x = 0.45 (T-S = 242 K; PM-Monoc/ FM-Ortho.I) with a Gaussian distribution in dS/dT, characteristic of a first-order phase transition. Near the purely magnetic transitions (PM/AFM) for x = 0 (T-N = 122 K) and x = 0.10 (TN = 127 K) we observe dS/dT peaks governed by spin fluctuation effects. A comparative analysis between dS/dT and the resistivity derivative d rho/dT near T-S is made. At low temperatures S(T) behaves similarly in the ferromagnetic x = 0.10 and 0.45 compounds (S approximate to AT + BT2), the anomalous B term being related to the mean internal field (spin wave excitations). For x = 0 (AFM phase at low T) one has S = AT (no B term; zero mean internal field).

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 4