The Competitive and Combining Effects of Grain Boundary and Fe/Mo Antisite Defects on the Low‐Field Magnetoresistance in Sr₂FeMoO₆

Abstract

Sr 2 FeMoO 6 ceramics with different Fe/Mo antisite defect (ASD) concentrations and grain-boundary (GB) properties were prepared. The competitive and combining effects of GB and Fe/Mo ASD on the transport and magnetoresistance were discussed. The GB properties, that is, intergrain coupling strength, positively related with resistivity value, is extremely sensitive to the total flux of reducing gas, in general, lower total gas flux leads to larger resistivity, thus stronger intergrain coupling strength, and then the contributions of GB effect to low-field magnetoresistance (LFMR) increase appreciably regardless of the amount of ASD. In detail, when ASD concentration is less than 26%, LFMR is dominantly controlled by the GB effect. However, the suppressed ASD effect on LFMR behavior comes to play when the ASD content is larger than or equal to 26%, where the GB and ASD effects contribute together to the LFMR. R. French-contributing editor Manuscript No. 33053. J ournalthe suppressed ASD effect on LFMR comes to play when ASD content is larger than or equal to 26%, where both GB effect and ASD effect contribute to LFMR behavior.

Challenges in Sr2FeMoO6−δ Thin Film Deposition

“…A suitable approximation is the ferromagnetic arrangement (FIM) model where Fe 3+ (3 d 5 , S = 5/2) ions in B‐sites are antiferromagnetically coupled to its six Mo 5+ (4 d 1 , S = 1/2) neighbors occupying the B′ sites. This approach is in good agreement with experimental data . This ideal arrangement produces a net magnetization of where m Fe and m Mo are the magnetic moments of Fe and Mo ions, respectively.…”

“…The correlation between M s and ASD defects has been widely studied . The degradation of both M s and T C with increasing ASD as well as the degradation of M s with increasing concentration of oxygen vacancies were predicted in ref.…”

“…At present, it is well established that in SFMO ceramics the main contribution to LFMR arises from spin‐dependent electron tunneling across insulating grain boundaries (GBs) and not by ASD . ASD comes into play solely at high levels of ASD ≥ 0.26 .…”

Estimation of the degree of crystallographic ordering of magnetoactive ions in Sr2FeMoO6-δ by means of the intensity of the X-ray peak (101)

“…2. Comparison of the calculated dependences of ASD (1-5) on the relative intensity of the peak (101) with published data ([6], [9], [16], [18], [25][26][27][28][29][30][31][32]) obtained by the analysis of X−ray diffraction patterns by the method Rietveld: (1) calculation without peak (200); (2) calculation taking into account the sum of the intensities of the peaks (112) − изменение параметров решетки тонких пленок за счет их несоответствия с подложкой;…”

“…В этом случае, степень заселения подрешеток катионами Fe и Mo определяется следующими формулами: , [9], [16], [18], [25][26][27][28][29][30][31][32]), полученными анализом рентгеновских дифрактограмм методом Ритвельда: Fig. 2.…”