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Lattice-distortion Induced Magnetic Transition from Low-temperature Antiferromagnetism to High-temperature Ferrimagnetism in Double Perovskites A2FeOsO6 (A = Ca, Sr).

Hou YS, Xiang HJ, Gong XG - Sci Rep (2015)

Bottom Line: High-temperature insulating ferrimagnetism is investigated in order to further reveal its physical mechanisms, as well as identify potentially important scientific and practical applications relative to spintronics.Also discussed is the 5d(3)-3d(5) superexchange.We propose that such superexchange is intrinsically antiferromagnetic instead of ferromagnetic as previously thought.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China.

ABSTRACT
High-temperature insulating ferrimagnetism is investigated in order to further reveal its physical mechanisms, as well as identify potentially important scientific and practical applications relative to spintronics. For example, double perovskites such as Sr2FeOsO6 and Ca2FeOsO6 are shown to have puzzling magnetic properties. The former is a low-temperature antiferromagnet while the latter is a high-temperature insulating ferrimagnet. In order to understand the underlying mechanisms, we have investigated the frustrated magnetism of A2FeOsO6 by employing density functional theory and maximally-localized Wannier functions. We find lattice distortion enhances the antiferromagnetic nearest-neighboring Fe-O-Os interaction, however weakens the antiferromagnetic interactions via the Os-O-O-Os and Fe-O-Os-O-Fe paths, so is therefore responsible for the magnetic transition from the low-temperature antiferromagnetism to the high-temperature ferrimagnetism as the decrease of the A(2+) ion radii. Also discussed is the 5d(3)-3d(5) superexchange. We propose that such superexchange is intrinsically antiferromagnetic instead of ferromagnetic as previously thought. Our work clearly illustrates the magnetic frustration can be effectively relieved by lattice distortion, thus paving the way for tuning of complex magnetism in yet other 3d-5d (4d) double perovskites.

No MeSH data available.


Related in: MedlinePlus

Dominant magnetic exchange paths and AF1, AF2 magnetic structures of Sr2FeOsO6.All magnetic exchange constants J are in units of meV. Figures (a,b) correspond to the I4/m-AF1 phase. Figures (c,d) correspond to the I4-AF2 phase. Figures (a,c) are the spin arrangement in the tetragonal ab plane. Figures (b,d) are the spin ordering along the c axis. Blue arrows represent spins. The relevant bond distances and angles obtained from DFT calculations are shown in (a–d).
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f4: Dominant magnetic exchange paths and AF1, AF2 magnetic structures of Sr2FeOsO6.All magnetic exchange constants J are in units of meV. Figures (a,b) correspond to the I4/m-AF1 phase. Figures (c,d) correspond to the I4-AF2 phase. Figures (a,c) are the spin arrangement in the tetragonal ab plane. Figures (b,d) are the spin ordering along the c axis. Blue arrows represent spins. The relevant bond distances and angles obtained from DFT calculations are shown in (a–d).

Mentions: Sr2FeOsO6 adopts two different magnetic and lattice structures depending on temperature21. With decreasing temperature, its magnetic structure transforms from AF1 into AF2 antiferromagnetism and its lattice structure transforms from I4/m into I4 with a dimerization between the NN Fe3+ and Os5+ ions along the c axis. In both AF1 and AF2, moments of Fe3+ and Os5+ ions are coupled antiparallel in the ab plane (Fig. 4a and Fig. 4c). In AF1 spins order as ++++ along the c axis (Fig. 4b). In AF2, spins order as ++−−++−− (Fig. 4d).


Lattice-distortion Induced Magnetic Transition from Low-temperature Antiferromagnetism to High-temperature Ferrimagnetism in Double Perovskites A2FeOsO6 (A = Ca, Sr).

Hou YS, Xiang HJ, Gong XG - Sci Rep (2015)

Dominant magnetic exchange paths and AF1, AF2 magnetic structures of Sr2FeOsO6.All magnetic exchange constants J are in units of meV. Figures (a,b) correspond to the I4/m-AF1 phase. Figures (c,d) correspond to the I4-AF2 phase. Figures (a,c) are the spin arrangement in the tetragonal ab plane. Figures (b,d) are the spin ordering along the c axis. Blue arrows represent spins. The relevant bond distances and angles obtained from DFT calculations are shown in (a–d).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4542468&req=5

f4: Dominant magnetic exchange paths and AF1, AF2 magnetic structures of Sr2FeOsO6.All magnetic exchange constants J are in units of meV. Figures (a,b) correspond to the I4/m-AF1 phase. Figures (c,d) correspond to the I4-AF2 phase. Figures (a,c) are the spin arrangement in the tetragonal ab plane. Figures (b,d) are the spin ordering along the c axis. Blue arrows represent spins. The relevant bond distances and angles obtained from DFT calculations are shown in (a–d).
Mentions: Sr2FeOsO6 adopts two different magnetic and lattice structures depending on temperature21. With decreasing temperature, its magnetic structure transforms from AF1 into AF2 antiferromagnetism and its lattice structure transforms from I4/m into I4 with a dimerization between the NN Fe3+ and Os5+ ions along the c axis. In both AF1 and AF2, moments of Fe3+ and Os5+ ions are coupled antiparallel in the ab plane (Fig. 4a and Fig. 4c). In AF1 spins order as ++++ along the c axis (Fig. 4b). In AF2, spins order as ++−−++−− (Fig. 4d).

Bottom Line: High-temperature insulating ferrimagnetism is investigated in order to further reveal its physical mechanisms, as well as identify potentially important scientific and practical applications relative to spintronics.Also discussed is the 5d(3)-3d(5) superexchange.We propose that such superexchange is intrinsically antiferromagnetic instead of ferromagnetic as previously thought.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China.

ABSTRACT
High-temperature insulating ferrimagnetism is investigated in order to further reveal its physical mechanisms, as well as identify potentially important scientific and practical applications relative to spintronics. For example, double perovskites such as Sr2FeOsO6 and Ca2FeOsO6 are shown to have puzzling magnetic properties. The former is a low-temperature antiferromagnet while the latter is a high-temperature insulating ferrimagnet. In order to understand the underlying mechanisms, we have investigated the frustrated magnetism of A2FeOsO6 by employing density functional theory and maximally-localized Wannier functions. We find lattice distortion enhances the antiferromagnetic nearest-neighboring Fe-O-Os interaction, however weakens the antiferromagnetic interactions via the Os-O-O-Os and Fe-O-Os-O-Fe paths, so is therefore responsible for the magnetic transition from the low-temperature antiferromagnetism to the high-temperature ferrimagnetism as the decrease of the A(2+) ion radii. Also discussed is the 5d(3)-3d(5) superexchange. We propose that such superexchange is intrinsically antiferromagnetic instead of ferromagnetic as previously thought. Our work clearly illustrates the magnetic frustration can be effectively relieved by lattice distortion, thus paving the way for tuning of complex magnetism in yet other 3d-5d (4d) double perovskites.

No MeSH data available.


Related in: MedlinePlus