Preparation of SrCoOx thin films on LaAlO3 substrate and their reversible redox process at moderate temperatures

Lin, Hai–Qing; Zhang, Z.F.; Xie, Xiaoxun; Wang, H.R.; Yu, Qin; Zhu, Hong

doi:10.1016/j.jcrysgro.2015.07.010

Cited by 14 publications

(12 citation statements)

References 28 publications

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“…So good ferromagnetism was observed in the film grown at moderate P O2 of 0.1 Pa. At low P O2 , though the concentration of Co-O v complexes was high due to the high concentration of O v , the ferromagnetism was weakened by the large film-substrate stains in these films. It has been reported that the strain could induce the ferromagnetic to antiferromagnetic phase transition in SrCoO x films [36,37] and that the large interfacial strain at the SrCoO x film/substrates could deteriorate the film ferromagnetism [38]. Thus, very weak ferromagnetism in the film with P O2 of 10 −4 Pa was observed in our work.…”

Section: Resultssupporting

confidence: 50%

Room-temperature ferromagnetism and oxygen pressure-dependent optical, ferromagnetic properties in SrSn_0.5Co_0.5O₃ thin films

Gao

2018

Materials Research Letters

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Room-temperature ferromagnetism was obtained in SrSn 0.5 Co 0.5 O 3 (SSCO) epitaxial film on SrTiO 3 substrate by pulsed laser deposition, and the effects of oxygen pressure (P O2 ) on the microstructure, optical and magnetic properties were examined. An interesting hybrid epitaxial film embedded with polycrystalline SSCO and SrCoO x nanoparticles was observed. The increase of P O2 relaxed the film/substrate compressive strain, promoted the growth of crystallites and reduced the optical band gap (from 2.43 to 1.68 eV). The SSCO film deposited at 0.1 Pa exhibited good ferromagnetism at 100-300 K, while the ferromagnetism in the film with higher and lower oxygen pressure (1 Pa and 10 −4 Pa) was weak. IMPACT STATEMENTRoom-temperature ferromagnetism and tunable optical band gap (2.34-1.68 eV) were demonstrated in Co-doped SrSnO 3 thin film grown on SrTiO 3 single-crystal substrate by pulsed laser deposition with varying oxygen pressure.

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Section: Resultssupporting

confidence: 50%

Room-temperature ferromagnetism and oxygen pressure-dependent optical, ferromagnetic properties in SrSn_0.5Co_0.5O₃ thin films

Gao

2018

Materials Research Letters

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“…Based on a structural model for SrCoO 2.75 suggested by experimental observation, 56 we constructed a structure containing only octahedra and tetrahedra. Adding two oxygen atoms to the SrCoO 2.5 BM-SCO unit cell and carrying out full-lattice relaxations, we obtained several stable structures for SrCoO 2.75 .…”

Section: Effective Exchange Interactions In Bm-scomentioning

confidence: 99%

Role of oxygen vacancy in the spin-state change and magnetic ordering in SrCoO3−δ

Lim

2018

Phys. Rev. B

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We present the first-principles investigation of the structural, electronic, and magnetic properties of SrCoO 3−δ (δ = 0, 0.25, 0.5) to understand the multivalent nature of Co ions in SrCoO 3−δ along the line of topotactic transition between perovskite SrCoO3 and brownmillerite SrCoO2.5. From the on-site Coulomb interaction Udependent ground state of stoichiometric SrCoO3, we show the proximity of its metallic ferromagnetic ground state to other antiferromagnetic states. The structural and magnetic properties of SrCoO 3−δ depending on their oxygen-content provide an interesting insight into the relationship between the Co-Co distances and the magnetic couplings so that the spin-state transition of Co spins can understood by the change of pd-hybridization depending on the Co-Co distances. The strong suppression of the dpσ-hybridization between Co d and O p orbitals in brownmillerite SrCoO2.5 brings on the high-spin state of Co 3+ d 6 and is responsible for the antiferromagnetically ordered insulating ground state. The increase of effective Co-Co distances driven by the presence of oxygen vacancies in SrCoO 3−δ is consistent with the reduction of the effective pd-hybridization between Co d and O p orbitals. We conclude that the configuration of neighboring Co spins is shown to be crucial to their local electronic structure near the metal-to-insulator transition along the line of the topotactic transition in SrCoO 3−δ . Incidentally, we also find that the I2mb symmetry of SrCoO2.5 is energetically stable and exhibits ferroelectricity via the ordering of CoO4 tetrahedra, where this polar lattice can be stabilized by the presence of a large activation barrier.

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“…14 Nevertheless, there are still a series of fundamental questions that need to be addressed for the development of successful SCO-based technologies. First, spontaneous reduction occurs in SCO at ambient conditions, 19 which is not desirable from an application perspective; whether epitaxial strain could have a blocking or a further accelerating effect on such an unwanted deterioration is yet unknown. Second, the dynamics and reversibility features of SCO redox reactions have been investigated only in a very reduced span of epitaxial strain conditions; 14,16 whether the same kind of fast and highly reversible redox reactions that have been observed in moderately tensile strained thin films may occur also at other epitaxial strains remains to be demonstrated.…”

Section: Introductionmentioning

confidence: 99%

Strain-Enhanced Oxygen Dynamics and Redox Reversibility in Topotactic SrCoO_3-δ (0 < δ ≤ 0.5)

Wang

Cazorla

et al. 2017

Chem. Mater.

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Oxide materials facilitating high-ion mobility and fast-ion transport are highly sought after for applications requiring intensive redox cycling. Some of these materials, in addition, may exhibit interesting multifunctional properties originating from electron correlation such as magnetism and metal–insulator transitions. SrCoO3‑δ (SCO) is one such compound, which recently has attracted a lot of interest due to its ability of taking on and releasing oxygen fluently. Here we investigate thoroughly the dynamics of oxygen vacancies and redox cycles in SCO under broad epitaxial strain conditions (−1.2% ≤ η ≤ +3.9%). We show that the capacity of this material to act as an “oxygen sponge” depends strongly on the strain conditions, with moderate strains of ca. +2% providing the optimal conditions for reversible redox cycling. First-principles simulation methods are employed to understand the experimental trends observed for SCO reduction in vacuum, and to provide microscopic insight into the formation of oxygen vacancies. Our work demonstrates that strain engineering can serve as an efficient means to control the dynamics of oxygen anions and redox reversibility in topotactic materials.

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Preparation of SrCoOx thin films on LaAlO3 substrate and their reversible redox process at moderate temperatures

Cited by 14 publications

References 28 publications

Room-temperature ferromagnetism and oxygen pressure-dependent optical, ferromagnetic properties in SrSn_0.5Co_0.5O₃ thin films

Room-temperature ferromagnetism and oxygen pressure-dependent optical, ferromagnetic properties in SrSn_0.5Co_0.5O₃ thin films

Role of oxygen vacancy in the spin-state change and magnetic ordering in SrCoO3−δ

Strain-Enhanced Oxygen Dynamics and Redox Reversibility in Topotactic SrCoO_3-δ (0 < δ ≤ 0.5)

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Preparation of SrCoOx thin films on LaAlO3 substrate and their reversible redox process at moderate temperatures

Cited by 14 publications

References 28 publications

Room-temperature ferromagnetism and oxygen pressure-dependent optical, ferromagnetic properties in SrSn0.5Co0.5O3 thin films

Room-temperature ferromagnetism and oxygen pressure-dependent optical, ferromagnetic properties in SrSn0.5Co0.5O3 thin films

Role of oxygen vacancy in the spin-state change and magnetic ordering in SrCoO3−δ

Strain-Enhanced Oxygen Dynamics and Redox Reversibility in Topotactic SrCoO3-δ (0 < δ ≤ 0.5)

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Room-temperature ferromagnetism and oxygen pressure-dependent optical, ferromagnetic properties in SrSn_0.5Co_0.5O₃ thin films

Room-temperature ferromagnetism and oxygen pressure-dependent optical, ferromagnetic properties in SrSn_0.5Co_0.5O₃ thin films

Strain-Enhanced Oxygen Dynamics and Redox Reversibility in Topotactic SrCoO_3-δ (0 < δ ≤ 0.5)