Magnetic Structure of SrFeO<sub>3</sub>

Takeda, Tomo; Yamaguchi, Yasuo; Watanabe, Hiroshi

doi:10.1143/jpsj.33.967

Cited by 300 publications

(168 citation statements)

References 9 publications

Supporting

Mentioning

157

Contrasting

Unclassified

Order By: Relevance

“…This φ is close to an observed one (φ=0.112). 6 With decreasing a, the G-type order becomes more stable, but with further decreasing a a transition from helical spin state to FM state occures irrespective of the type of order, i.e., the φ at minimum energy becomes zero when a changes from 3.75Å to 3.70Å in both the A-and G-type orders. This result is qualitatively consistent with the experimental results of a transition from AFM to FM induced by pressure.…”

mentioning

confidence: 92%

Pressure-induced ferromagnetism in cubic perovskite SrFeO3and BaFeO3

Li¹,

Iitaka²,

Tohyama³

2012

Phys. Rev. B

View full text Add to dashboard Cite

The spin order in cubic perovskite SrFeO3 and BaFeO3 under high pressure is studied by density functional theory (DFT) calculation with local spin density approximation plus Hubbard U (LSDA+U ). At ambient pressure, A-type and G-type helical spin orders are almost degenerate in BaFeO3 whose lattice constant is 3.97Å. When the lattice constant is reduced to 3.85Å which is same as the lattice constant of SrFeO3 at ambient pressure, G-type helical spin order becomes stable, being consistent with SrFeO3. This is because superexchange interaction is enhanced as compared with double exchange interaction. Phase transition from helical spin state to ferromagnetic state in both SrFeO3 and BaFeO3 takes place if the lattice constant is further reduced to 3.70Å. This is because reduced local spin moment weakens the contribution from superexchange interaction. Our result agrees with recent experimental result of BaFeO3 under high pressure. Additionally, our calculation predicts that half-metal BaFeO3 at ambient pressure will become a good metal under high pressure.PACS numbers: PACS numbers: 75.30.Et, 75.50.Bb, 75.40.Mg Helical spin order in cubic perovskite AFeO 3 (A=Ca, Sr, Ba), where Fe 4+ is in a high spin configuration d 4 , has attracted lots of research interest for their potential application in spintronic devices. 1-3 All of them present helical spin order below 115 K, 134 K, and 111 K for A=Ca, Sr, and Ba, respectively. 4-7 The Fe3d electrons in these materials can be divided into two classes: conducting and localized electrons. Three localized electrons occupy t 2g orbitals and one electron occupies double degenerated e g orbitals. The interaction between conducting electron and localized electron is described by Hund coupling. In addition, charge-transfer energy ∆ defined as the energy cost to move an electron from oxygen 2p orbital to Fe3d orbitals shows a negative value, [8][9][10] implying that metallic conduction mainly occurs on oxygen band. The helical spin order can be understood from the competition of double exchange (DE) and superexchange (SE) interactions, the former and the latter of which favors ferromagnetism (FM) and anti-ferromagnetism (AFM), respectively. 11,12 It is well-known that electronic structure is tunable under high pressure. Phase transition from helical spin state to FM state in SrFeO 3 under the pressure of 7 GPa has been reported. 13 Very recently, the evolution of spin order in BaFeO 3 under pressure has been studied. 14 At ambient pressure, BaFeO 3 shows helical spin order, which changes to FM under very weak external magnetic field, ∼0.3 T. 7 The helical spin order is stabilized with increasing pressure, but FM finally becomes stable under pressure above 30 GPa. There is no structural phase transition, since the cubic symmetry of BaFeO 3 preserves up to 50 GPa. The electrical resistance decreases under high pressure.Hydrostatic pressure P reduces the lattice constant a in AFeO 3 . The compression of a leads to the increase of the hopping integral pdσ representing the hybridiza...

show abstract

mentioning

confidence: 92%

Pressure-induced ferromagnetism in cubic perovskite SrFeO3and BaFeO3

Li¹,

Iitaka²,

Tohyama³

2012

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…Recent photoemission studies have revealed that the electronic structure of Fe 4+ oxides is rather unique: the charge-transfer energy ∆, the energy required to transfer an electron from the oxygen p to the Fe 3d level, is extremely negative (∼ −3 eV including Hund's coupling energy) [11], and the ground state of the formal Fe [12], the Co-substitution induced ferromagnetism in SrFe 1−x Co x O 3 [13,14], and magnetic and electric phase transitions under high pressure [15,16,17], therefore, one has to take into account the negative ∆, namely, the oxygen-hole character of charge carriers. A polycrystalline sample of CaFeO 3 was prepared by a solid state reaction and a subsequent treatment under high-pressure oxygen [13].…”

mentioning

confidence: 99%

Different routes to charge disproportionation in perovskite-type Fe oxides

et al. 2002

View full text Add to dashboard Cite

Iron perovskites CaFeO3 and La0.33Sr0.67FeO3 show charge disproportionation, resulting in charge-ordered states with Fe 3+ :Fe 5+ = 1 : 1 and = 2 : 1, respectively. We have made photoemission and unrestricted Hartree-Fock band-structure calculation of CaFeO3 and compared it with La0.33Sr0.67FeO3. With decreasing temperature, a gradual decrease of the spectral weight near the Fermi level occurred in CaFeO3 as in La0.33Sr0.67FeO3 although lattice distortion occurs only in CaFeO3. Hartree-Fock calculations have indicated that both the breathing and tilting distortions are necessary to induce the charge disproportionation in CaFeO3, while no lattice distortion is necessary for the charge disproportionation in La0.33Sr0.67FeO3. has revealed a spin-density wave (SDW) of six-fold periodicity along the 111 direction with two inequivalent spin states of Fe, suggesting a charge-density wave (CDW) of three-fold periodicity along the same direction.Recent photoemission studies have revealed that the electronic structure of Fe 4+ oxides is rather unique: the charge-transfer energy ∆, the energy required to transfer an electron from the oxygen p to the Fe 3d level, is extremely negative (∼ −3 eV including Hund's coupling energy) [11], and the ground state of the formal Fewhere L denotes a hole in the oxygen 2p band. The charge disproportionation is therefore more correctly described as 2d To understand the interesting physical properties of Fe 4+oxides such as the helical antiferromagnetic metallic state in SrFeO 3 [12], the Co-substitution induced ferromagnetism in SrFe 1−x Co x O 3 [13,14], and magnetic and electric phase transitions under high pressure [15,16,17], therefore, one has to take into account the negative ∆, namely, the oxygen-hole character of charge carriers. Especially, the d 5 L ground state naturally explains the fact that SrFeO 3 shows no charge disproportionation yet no Jahn-Teller effect since the d 4 ion necessarily undergoes a Jahn-Teller distortion.In a recent photoemission and unrestricted Hartree-Fock band-structure calculation study of La 1−x Sr x FeO 3 [18], we have shown that the charge disproportionation is purely electronically driven and that the ordering of oxygen holes plays an important role in the charge disproportionated state of La 0.33 Sr 0.67 FeO 3 . In this Letter, we present a photoemission study of CaFeO 3 , which unlike La 0.33 Sr 0.67 FeO 3 shows a breathing-type lattice distortion in the charge disproportionated state. Using photoemission we have studied how the charge disproportionation influences the electronic structure near the Fermi level (E F ) in comparison with La 0.33 Sr 0.67 FeO 3 . We have also

show abstract

“…14) Oxygen-deficient strontium cobaltite (SrCoO 2.5 ) with Brownmillerite structure is known as insulating non-magnet, but it is changed into SrCoO 3 with Perovskite structure, which is a ferromagnetic metal, by the oxidation. 15) Thus, the chemical modification of TMOs is the most reasonable way to demonstrate the functional switching devices, but the control of oxygen off-stoichiometry or protonation of TMOs is not typically utilized for solid-state devices because of imperative high-temperature heat treatment under an oxidative/reductive atmosphere. 16)20) Meanwhile, the electrochemical redox reaction by the electrolysis in liquid electrolyte has been a facile method to achieve the chemical modification at room temperature (RT), 21) but such a device has not been realized because of the lack of a liquid-leakage-free electrolyte.…”

Section: )3)mentioning

confidence: 99%

“…Electro-magnetic phase switching device 27) SrCoO x (SCO x ) is classically known to show different electromagnetic properties depending on the oxygen composition (x), which can be varied in the range of 2.53.0, with keeping the crystallographic lattice structure. 15), 49) The most stable phase of SCO 2.5 possesses an oxygen-vacancy ordered brownmillerite (BM-) structure. The fully-oxidized SCO 3 phase, which can be synthesized under high oxygen-pressure and high temperature conditions, has simple perovskite (P-) structure.…”

Section: Electrochromic Metal-insulatormentioning

confidence: 99%

See 1 more Smart Citation

Transition-metal-oxide based functional thin-film device using leakage-free electrolyte

Katase

Ohta

2017

J. Ceram. Soc. Japan

View full text Add to dashboard Cite

Using the flexible valence states of transition-metal-oxides (TMOs), the optical, electronic, and magnetic properties can be simultaneously controlled by electrochemical oxidation and reduction. Herein we review our recent works on the electrochemically switchable functional thin-film device, which has a three-terminal thin-film-transistor (TFT) structure with the TMO as an active channel layer and the liquid-leakage-free electrolyte as a gate insulator. Thin films of vanadium dioxide, tungsten trioxide, and strontium cobaltite were selected as the channel layer. By applying the gate voltage at room temperature in air, the protonation/ deprotonation or oxidation/deoxidation occurs in the TMO channels and their opto-electronic and electro-magnetic properties are reversibly switched by using the mobile ions in the solid TFT structure. The present device with liquid-leakage-free electrolyte provides a novel design concept for the development of future multifunctional switching devices based on TMOs.

show abstract

Magnetic Structure of SrFeO₃

Cited by 300 publications

References 9 publications

Pressure-induced ferromagnetism in cubic perovskite SrFeO3and BaFeO3

Pressure-induced ferromagnetism in cubic perovskite SrFeO3and BaFeO3

Different routes to charge disproportionation in perovskite-type Fe oxides

Transition-metal-oxide based functional thin-film device using leakage-free electrolyte

Contact Info

Product

Resources

About

Magnetic Structure of SrFeO3

Cited by 300 publications

References 9 publications

Pressure-induced ferromagnetism in cubic perovskite SrFeO3and BaFeO3

Pressure-induced ferromagnetism in cubic perovskite SrFeO3and BaFeO3

Different routes to charge disproportionation in perovskite-type Fe oxides

Transition-metal-oxide based functional thin-film device using leakage-free electrolyte

Contact Info

Product

Resources

About

Magnetic Structure of SrFeO₃