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Wójcik, Marek J.; Jędryka, E.; Nadolski, S.; Navarro, J.; Rubi, D.; Fontcuberta, J.

doi:10.1103/physrevb.69.100407

Cited by 44 publications

(45 citation statements)

References 21 publications

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“…[3], where such assignment has been made based on the slope of NMR frequency shift in the external magnetic field. A detailed discussion of the spectrum structure exceeds the scope of the present paper and will be addressed elsewhere [4].…”

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confidence: 99%

Mo–Fe antisite defects in Sr2FeMoO6 studied by NMR

Wójcik

Jędryka

Nadolski

et al. 2004

Journal of Magnetism and Magnetic Materials

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confidence: 99%

Mo–Fe antisite defects in Sr2FeMoO6 studied by NMR

Wójcik

Jędryka

Nadolski

et al. 2004

Journal of Magnetism and Magnetic Materials

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“…La substitution was found to increase the Curie temperature and also the number of defects ( [5,6] and [7]). It also increases the Mo hyperfine field value [8]. For the Fe-Mo double perovskite, the ferrimagnetic antiparallel ordering between the Fe and Mo atoms is caused by a double exchange-like interaction (DE) which originates from the t 2g spin down electron hopping between Fe 2+/3+ and Mo…”

Section: Introductionmentioning

confidence: 99%

NMR Study of (Sr,Ba,La)₂Fe_1+yMo_1-yO₆Double Perovskites

et al. 2004

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The 95 Mo and 97 Mo NMR spin-echo study of (Sr,Ba,La) 2 Fe 1+y Mo 1−y O 6 double perovskites is reported. Powder samples of Ba 1.44 Sr 0.36 La 0.2 FeMoO 6 and (Ba0.8Sr0.2)2−2xLax#xFe1+yMo1−yO6, where # denotes vacancies, for: x = 0, y = 0; x = 0.1, x = 0.2 and x = 0.3, y = 0 and y = 0.2 were measured at 4.2 K and no applied magnetic field. NMR signals are observed at 55-100 MHz for the main line and 30-55 MHz for low-frequency satellite. The main line and the satellite are attributed to the ideal and defect positions of Mo atoms. La and vacancy doping introduce more defects, however, increasing the Fe/Mo ratio decreases the amount of defect Mo sites. La doping causes a satellite pattern at the high frequency side of the spectrum, which is related to different numbers of the La next neighbours. The effect is attributed to an increase in the electron density and the corresponding magnetic moment at the adjacent Mo sites and reveals a local character of the electron doping.

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“…In all the cases, the observed main line is in the range of 50-80 MHz, and in the range of 30-60 MHz for low frequency satellites, Fig. 1, which are attributed to the ideal and defect sites of Mo ions, respectively [43,20,44]. For Ba 2 FeMoO 6 the signal observed at 63.1(2) MHz is attributed to 57 Fe as derived from the measurements in the applied field which are discussed below.…”

Section: Molybdenum Nmr Results and Discussionmentioning

confidence: 69%

Local Magnetic and Electronic Properties of the A2FeM'O6 (A = Ba, Sr, Ca, M' = Mo, Re) Double Perovskites

et al. 2007

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The results of a combined NMR, X-ray absorption spectroscopy and X-ray magnetic circular dichroism study of the AA FeMoO6 and AA FeReO6 double perovskites are presented. They revealed a dependence of electronic and magnetic properties, including a d-electron transfer between Fe and Mo sites, on the structural tolerance factor. The maximum value of the 4d Mo electron occupation and the corresponding Mo moment is obtained for the tolerance factor of unity. This corresponds to the maximum strength of the magnetic interaction and, respectively, to the Curie temperature. The dominant T 5/2 type temperature dependence of the Mo hyperfine field reveals the half-metallicity of the AA FeMoO 6 compounds. Antisite defects and antiphase boundaries have been identified in NMR measurements and the strength of their magnetic coupling have been determined. A considerable orbital contribution to the Re and Fe magnetic moments were found in the NMR and X-ray magnetic circular dichroism measurements on the AA FeReO6 compounds. Its magnitude decreases with increasing structural tolerance factor and is correlated with their magnetic anisotropy. IntroductionDouble perovskites (DP) of a general formula A 2 MM O 6 , where A is an alkaline earth, and M and M are 3d, 4d, and/or 5d transition metals belong to a very broad family of oxide compounds crystallising in the perovskite structure. They exhibit intriguing magnetic and electronic properties including half metallicity, a considerable low field magnetoresistance (LFMR) and a variety of magnetic structures, see review paper [1]. Magnetic and electronic properties are closely interrelated, due to the same (d) character of the "magnetic" and "conduction" electrons. Exchange interactions can occur between ions of the same element, as e.g. in manganese perovskites, as well as between ions of different elements, as e.g. in double perovskites. The interplay of lattice, charge, and spin degrees of freedom causes a variety of electronic and magnetic properties ranging from a metallic ferro-or ferrimagnetism to antiferromagnetic or paramagnetic insulating behaviour. This also brings about the magnetoresistive properties of the compounds.The interplay between magnetic and electronic transport properties in these systems can be controlled by substitution of alkaline earths (e.g. Ba, Sr, Ca) or lanthanides (e.g. La, Pr, Nd) in the A-site, as well as by the substitution of transition metals (e.g. Fe, Cr, Mn, Mo, Rh, Ru, W, Re). Among the double perovskites, the Fe-Mo and Fe-Re compounds, which are the subject of the study presented in this paper, have recently attracted a great deal of interest among the researchers. Their relatively high magnetic ordering temperature (in most cases higher than the room temperature) compared to that of manganese perovskites, and a significant LFMR make them especially interesting for applications, e.g. in magnetoelectronics or spintronics. The LFMR is explained in terms of intergranular tunneling MR (ITMR), and is related to the half-metallic nature of the ground...

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NMR evidence for selective enhancement of Mo magnetic moment by electron doping inSr2−xLax

Cited by 44 publications

References 21 publications

Mo–Fe antisite defects in Sr2FeMoO6 studied by NMR

Mo–Fe antisite defects in Sr2FeMoO6 studied by NMR

NMR Study of (Sr,Ba,La)₂Fe_1+yMo_1-yO₆Double Perovskites

Local Magnetic and Electronic Properties of the A2FeM'O6 (A = Ba, Sr, Ca, M' = Mo, Re) Double Perovskites

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NMR evidence for selective enhancement of Mo magnetic moment by electron doping inSr2−xLax

Cited by 44 publications

References 21 publications

Mo–Fe antisite defects in Sr2FeMoO6 studied by NMR

Mo–Fe antisite defects in Sr2FeMoO6 studied by NMR

NMR Study of (Sr,Ba,La)2Fe1+yMo1-yO6Double Perovskites

Local Magnetic and Electronic Properties of the A2FeM'O6 (A = Ba, Sr, Ca, M' = Mo, Re) Double Perovskites

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NMR Study of (Sr,Ba,La)₂Fe_1+yMo_1-yO₆Double Perovskites