n‐ to p‐type Sr 2 Fe 1+x Re 1‐x O 6 double perovskites: magnetoresistance and magnetoSeebeck

• Published in: Zeitschrift für anorganische und allgemeine Chemie (1950) Vol. 649; no. 5
• Main Authors: Hébert, Sylvie, Carbonio, Raul, Martin, Christine, Maignan, Antoine
• Format: Journal Article
• Language: English
• Published: 01.03.2023
• ISSN: 0044-2313; 1521-3749
• DOI: 10.1002/zaac.202200324

Abstract The T‐dependent Seebeck (S) of several samples belonging to the Sr 2 Fe 1+x Re 1‐x O 6 series (x≤0.33) has been investigated. All these polycrystalline samples synthesized by solid state reaction in closed vessels crystallize in the I4/m double perovskite structure. Though ferrimagnetic with T C >400 K, the decrease of their magnetization as x increases from x=0.00 is explained by the cation disorder induced by the deviation from the ideal 1 : 1 Re/Fe ratio for the 2a and 2b crystallographic sites. Interestingly, it is found that at room temperature, the S sign changes from S>0 to S<0 as x increases to about x=0.25. Despite that the magnitude of their magnetoresistance, near −20 % in 9T and at T=5 K, is not very sensitive to x, a positive magneto Seebeck effect is observed only for the samples exhibiting S(300 K)>0. This asymmetry in the magnetothermopower properties of the n‐ and p‐type samples is interpreted in the framework of the spin polarized transport of these magnetoresistive double‐perovskites.