Band filling versus bond bending in substituted LxSr2−xFeMoO6(L=Ca, La, Nd) compounds

With the aim of determining and discriminating the influence of both steric and band-filling effects on the strength of the magnetic interactions of double perovskites, we have studied the structural and magnetic properties of substituted LxSr2−xFeMoO6 (L=Ca, La, and Nd) compounds. Our results show that the raising of Curie temperature in electron-doped samples (La and Nd substitutions) is mainly due to band-filling effects, being the influence of structural distortions (steric effects) is of less relevance. This fact contrasts with the well-known properties of manganites, where a strong correlation between structural properties and magnetic interactions is present. We argue that this disagreement relies on the different symmetries of the electronic orbitals involved in the magnetic interactions in both cases.

[1]  Mart́ınez,et al.  Colossal magnetoresistance of ferromagnetic manganites: Structural tuning and mechanisms. , 1996, Physical review letters.

[2]  Ll. Balcells,et al.  Raising the Curie temperature in Sr2FeMoO6 double perovskites by electron doping , 2001 .

[3]  J. Fontcuberta,et al.  Configurational disorder and magnetism in double perovskites: A Monte Carlo simulation study , 2004 .

[4]  Manuel Ricardo Ibarra,et al.  Large low-field magnetoresistance and TC in polycrystalline (Ba0.8Sr0.2)2-xLaxFeMoO6 double perovskites , 2002 .

[5]  R. D. Shannon.  Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides , 1976 .

[6]  L. A. Fernandez,et al.  Phase diagram and influence of defects in the double perovskites , 2003 .

[7]  J. M. Chen,et al.  Chemical Tuning of Structure, Magnetization, and Conductivity in the Self-doped Double-Perovskite (Sr2-xCax)FeMoO6 (0 ≤ x ≤ 2.0) System , 2003 .

[8]  M. Ibarra,et al.  Structural and magnetic properties of double perovskites AA'FeMoO6 (AA' = Ba2, BaSr, Sr2 and Ca2) , 2000 .

[9]  Juan Rodríguez-Carvajal,et al.  Recent advances in magnetic structure determination by neutron powder diffraction , 1993 .

[10]  J. Fontcuberta,et al.  Antisites and electron-doping effects on the magnetic transition of Sr 2 FeMoO 6 double perovskite , 2003 .

[11]  Naoki Kobayashi,et al.  Continuous excitation of planetary free oscillations by atmospheric disturbances , 1998, Nature.