Suppression of magnetic phase separation in epitaxial SrCoO<sub>X</sub> films

Rueckert, F. J.; Nie, Yuefeng; Abughayada, C.; Sabok-Sayr, S. A.; Mohottala, Hashini; Budnick, J. I.; Hines, W. A.; Dąbrowski, B.; Wells, B. O.

doi:10.1063/1.4801646

Cited by 10 publications

(11 citation statements)

References 31 publications

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“…As a result these films displayed i.) a well known FM behavior under low tensile strain when grown on STO, which has been well established for SCO in bulk [12][13][14] (T C = 280-305 K) and in epitaxial films under a lower degree of tensile strain 1,2,16 and ii.) G-type AFM ordering under large tensile strain when deposited on DSO.…”

Section: -33mentioning

confidence: 95%

Strain-induced magnetic phase transition inSrCoO3−δthin films

Callori

Bertinshaw

et al. 2015

Phys. Rev. B

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It has been well established that both in bulk at ambient pressure and for films under modest strains, cubic SrCoO 3−δ (δ < 0.2) is a ferromagnetic metal. Recent theoretical work, however, indicates that a magnetic phase transition to an antiferromagnetic structure could occur under large strain accompanied by a metal-insulator transition. We have observed a strain-induced ferromagnetic to antiferromagnetic phase transition in SrCoO 3−δ films grown on DyScO3 substrates, which provide a large tensile epitaxial strain, as compared to ferromagnetic films under lower tensile strain on SrTiO3 substrates. Magnetometry results demonstrate the existence of antiferromagnetic spin correlations and neutron diffraction experiments provide a direct evidence for a G-type antiferromagnetic structure with Neél temperatures between TN ∼ 135 ± 10 K and ∼ 325 ± 10 K depending on the oxygen content of the samples. Therefore, our data experimentally confirm the predicted strain-induced magnetic phase transition to an antiferromagnetic state for SrCoO 3−δ thin films under large epitaxial strain.The broad range of transition metal oxide functionalities, including superconductivity, magnetism, and ferroelectricity, can be tuned by the careful choice of parameters such as strain, oxygen content, or applied electric and magnetic fields 1-9 . This tunability makes transition metal oxide materials ideal candidates for use in developing novel information and energy technologies 10,11 . SrCoO 3 is a particularly interesting system for investigation. SrCoO 3−δ has long been studied due to its propensity to form oxygen-vacancy-ordered structures as the oxygen content is decreased. The system undergoes well-defined structural phase transitions between distinct topotactic phases, from a cubic perovskite phase at SrCoO 3 to brownmillerite SrCoO 2.5 . The ties between the structural and functional properties of the material are obvious as a magnetic phase transition from ferromagnetic (FM) SrCoO 3.0 with T C = 280-305 K to antiferromagnetic (AFM) SrCoO 2.5 with T N = 570 K accompanies the structural transition 5,[12][13][14] . This is similar to the case of SrFeO 3−δ , which has also been demonstrated to undergo oxygen vacancy ordering with magnetic phase transitions related to the structure and Fe charge ordering [17][18][19] .In addition to oxygen stoichiometry, other possibilities, such as strain or applied magnetic or electric fields, may be used to tune the system. Lee and Rabe have simulated the effect of epitaxial strain on SrCoO 3.0 and predict a large polar instability resulting in a dependence of the magnetic structure on strain 20,21 . Their results show that the magnetic state can be controlled by the amount of compressive or tensile strain applied. An AFM-FM transition is predicted at both, tensile strain of ∼2.0 % and compressive strain of approximately -0.8 %, which is caused through the Goodenough-Kanamori rules as a consequence of simultaneous structural phase transitions between phases with different distortions and rotational pa...

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Section: -33mentioning

confidence: 95%

Strain-induced magnetic phase transition inSrCoO3−δthin films

Callori

Bertinshaw

et al. 2015

Phys. Rev. B

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“…As a result, coexistence of SrCoO 2.5 and SrCoO 3À δ phases is confirmed within the film deposited on STO substrate, which has also been observed in other studies (Refs. [13] and [14]). Now the difference between the XRD patterns of SCO films on LAO and STO substrates reveals that the negative lattice mismatch prefers to retain oxygen content as expected.…”

Section: Structural Evolution Of the Sco Films With Lattice Mismatchmentioning

confidence: 95%

“…While epitaxial SrCoO 2.5 films are rather easy to be prepared, epitaxial growth of SrCoO 3 is very difficult because the energetic Co 4 þ valence state prefers to convert to the stable Co 2 þ and/or Co 3 þ states at ambient conditions. Furthermore, considering that epitaxial films usually have identical in-plane lattice parameters with substrates, the reported highly/fully oxidized T [11]-or C [9,[11][12][13][14] -SCO films were under tensile strain (positive lattice mismatch). Meanwhile, it is known that the unit cell of SCO expands with increasing oxygen deficiency due to the larger radius of Co 3 þ in Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jcrysgro comparison with Co 4 þ [16].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, many efforts have been focused on the epitaxial growth of SrCoO x (SCO, x¼ 2.5-3.0) to gain more insight into its oxygen evolution [9,[11][12][13][14]. Considering the fact that the SrCoO 2.5 has an orthorhombic structure with a o ¼ 5.5739, b o ¼5.4697, and c o ¼15.7450 Å, which can be represented as a pseudo-tetragonal structure with a pt ¼ b pt ¼3.905, and c pt ¼3.9363 Å [15], and the lattice parameter of cubic SrCoO 3 is a c ¼3.8289 Å [10], former researchers usually deposited the films on SrTiO 3 (STO, a c ¼3.905 Å) or (LaAlO 3 ) 0.3 -(SrAl 0.5 Ta 0.5 O 3 ) 0.7 (LSAT, a c ¼3.868 Å) substrates which provide a good lattice match to SrCoO 2.5 and SrCoO 3 , respectively.…”

Section: Introductionmentioning

confidence: 99%

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

Lin

Zhang

Xie

et al. 2015

Journal of Crystal Growth

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“…[2][3][4][5][6][7][8][9][10][11] The use of aggressive reducing agents, such as Ca 2 H, 12 has enabled the realization of ABO 2 compounds such as SrFeO 2 and LaNiO 2 via topotactic transformations from as-grown ABO 3 and ABO 2.5 films. 13,14 Given the sensitive coupling between δ and physical properties, [15][16][17] topotactic oxidation and reduction reactions have been used to induce large changes to the electronic, optical, and magnetic properties of epitaxial films [18][19][20] and may prove applicable in ionically controlled solid state devices. [21][22][23][24] A second class of topotactic reaction involves the insertion or substitution of a different anion on the oxygen site to stabilize mixed-anion perovskites such as oxyfluorides.…”

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confidence: 99%