Magnetic and structural properties of the double-perovskite Ca2FeReO6

Westerburg, W.; Lang, O.; Ritter, C.; Felser, Claudia; Tremel, Wolfgang; Jakob, G.

doi:10.1016/s0038-1098(02)00079-0

Cited by 72 publications

(60 citation statements)

References 12 publications

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“…The resulting total Re moment is antiferromagnetically coupled to the Fe moment and is estimated at m tot ≈ 0.8 µ B , in good agreement with the recent NMR [20] and neutron diffraction results [37]. Moreover, the spin moment of order of 1.1 µ B is consistent with the predictions of local spin density calculations [29,31].…”

Section: X-mcd Results and Discussionsupporting

confidence: 88%

“…538 K and 635 K in Ca 2 FeReO 6 and Sr 2 CrReO 6 , respectively [35]. They show even larger variety of magnetic and transport properties than those of Mo-based double perovskites due to an additional electron in the spin-down subband and a stronger spin-orbit coupling in heavier Re ion [35][36][37][38][39]. Although the spin moment of the additional electron decreases the bulk magnetic moment from ≈ 4 µ B in AA FeMoO 6 to ≈ 3 µ B in AA FeReO 6 double perovskites, its influence on the strength of ferromagnetic interaction seems to be weak, since the Curie temperatures of Sr 2 FeMoO 6 and Sr 2 FeReO 6 are almost identical, i.e.…”

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confidence: 99%

“…Smaller r A ions lead to lattice distortion and lowering of the local symmetry from cubic (AA = Ba 2 ) to tetragonal (AA = Sr 2 ) and monoclinic/orthorhombic (AA = Ca 2 ) in Re/Mo-based compounds. Then, the Mo-based compounds preserve their weak metallicity, whereas Re-based double perovskites of monoclinic symmetry show semiconducting behaviour and undergo a structural transition at low temperatures, which further increases their resistivity [35,[37][38][39]. The difference in their magnetic properties is especially intriguing.…”

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confidence: 99%

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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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Section: X-mcd Results and Discussionsupporting

confidence: 88%

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confidence: 99%

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confidence: 99%

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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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“…6 The aim of the present study was to find out whether a significant Re orbital moment exists in Re-Fe double perovskites and how the lattice distortion influences its value. Moreover, our experiments provide the direct quantitative information about the total magnetic moment of Re ions unlike previous measurements with neutron diffraction, 5 Mössbauer, 2,4 and nuclear magnetic resonance ͑NMR͒ spectroscopies, 11 as well as band structure calculations. 10,12,13 For example, the calculated and measured total magnetic moment of Re is always antiparallel to that of Fe, but its value reported for Sr 2 FeReO 6 ranges from 0.16 B to 1.27 B .…”

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confidence: 89%

“…; BBЈ = FeMo, FeRe, CrRe, CrW, etc.͒ are being intensively studied in order to find a material with optimal performance. [2][3][4][5][6][7] Among them the Re-based double perovskites are the most promising compounds in terms of high Curie temperature, e.g., 538 and 635 K in Ca 2 FeReO 6 and Sr 2 CrReO 6 , respectively. 3 Moreover, Re-based double perovskites are magnetically hard 4,6,8 and reveal large magnetoelastic effects, 9 which can only be explained by a substantial magnetocrystalline anisotropy due to the anisotropy of an unquenched orbital moment of Re.…”

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Evidence of unquenched Re orbital magnetic moment in AA′FeReO6 double perovskites

Sikora

Kapusta

Borowiec

et al. 2006

Applied Physics Letters

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Spin and orbital magnetic moments of rhenium in AAЈFeReO 6 double perovskites ͑A , AЈ = Ba, Sr, and Ca͒ have been directly probed employing x-ray magnetic circular dichroism at the Re L 2,3 edges. A considerable orbital magnetic moment is observed in all the compounds studied, which confirm theoretical predictions of unquenched Re orbital moment despite its octahedral coordination. Relative orbital-to-spin moment ratio alters with lattice distortion from m L / m S = −0.285 to − 0.337 from Ba 2 FeReO 6 to Ca 2 FeReO 6 , respectively. Moreover, the spin moment of Re ion scales with Curie temperature, the most relevant property in spin electronics application of the compounds studied. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2234292͔ Ordered double perovskites have recently attracted great interest due to their large spin polarization and Curie temperature ͑T C ͒ much higher than room temperature. These properties are strongly desired in order to realize reasonable magnetoresistance effects at room temperature, which is not only a challenging subject of fundamental science but also an important phenomenon for potential applications in spin electronics. Therefore the first observation of substantial magnetoresistance at room temperature in Sr 2 FeMoO 6 ͑Ref. 1͒ quickly led to production of magnetic tunnel junctions and magnetoresistive potentiometers.Currently, the other ordered double perovskites AAЈBBЈO 6 ͑A , AЈ = Ca, Sr, Ba, La, etc.; BBЈ = FeMo, FeRe, CrRe, CrW, etc.͒ are being intensively studied in order to find a material with optimal performance. 2-7 Among them the Re-based double perovskites are the most promising compounds in terms of high Curie temperature, e.g., 538 and 635 K in Ca 2 FeReO 6 and Sr 2 CrReO 6 , respectively.3 Moreover, Re-based double perovskites are magnetically hard 4,6,8 and reveal large magnetoelastic effects, 9 which can only be explained by a substantial magnetocrystalline anisotropy due to the anisotropy of an unquenched orbital moment of Re.

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Transition Metal Oxides: Magnetoresistance and Half‐Metallicity

Mandal¹,

Greenblatt²

2010

Functional Oxides

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Magnetic and structural properties of the double-perovskite Ca2FeReO6

Cited by 72 publications

References 12 publications

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

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

Evidence of unquenched Re orbital magnetic moment in AA′FeReO6 double perovskites

Transition Metal Oxides: Magnetoresistance and Half‐Metallicity

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