Molecular beam epitaxy and microstructural study of La<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow /><mml:mrow><mml:mn>2</mml:mn><mml:mi>−</mml:mi><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>Sr<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow /><mml:mrow><mml:mn>1</mml:mn><mml:mo>+</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>Cu<mml:math xmlns:mml="http

Verbist, K.; Milat, Ognjen; Tendeloo, Gustaaf Van; Arrouy, F.; Williams, E. J.; Rossel, C.; Machler, E; Locquet, Jean‐Pierre

doi:10.1103/physrevb.56.853

Cited by 2 publications

(3 citation statements)

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“…Thus, a wide scope of experimental material has been reported on MBE growth of metastable superconducting cuprates and superlattices (see Bozovic and Eckstein, Verbist et al, Balestrino et al, and Yamamoto et al …”

Section: Introductionmentioning

confidence: 99%

Epitaxial Stabilization of Oxides in Thin Films

et al. 2002

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A survey of recent experimental results is given, presenting the growth of oxide epitaxial thin films in P−T−x conditions, which are far from those necessary for the existence of corresponding phases in a bulk state. The unstable in bulk BaCu3O4, NdMn7O12, RNiO3, and unusual polymorphous forms of BaRuO3, RMnO3, TiO2, and Mn3O4 are some examples. The stabilizing effect is observed only if epitaxial growth is induced. A rich variety of the effect observations are demonstrated to be of a thermodynamic origin, rather than of a kinetic one. Epitaxial stabilization is shown to be the result of the low energy of coherent interfaces formed due to epitaxy.

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Section: Introductionmentioning

confidence: 99%

Epitaxial Stabilization of Oxides in Thin Films

et al. 2002

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“…La 2−x (Sr,Ca) 1+x Cu 2 O 6+δ (La2126) is a good bilayer compound for the study of epitaxial growth, because this compound has a simpler crystal structure than YBCO and BSCCO. A few results on thin-film growth of La2126 on SrTiO 3 (100) have been reported, 3,4 but unfortunately superconducting films have never been obtained. As is widely known, La2126-type structure can be rather easily obtained by a conventional solid-state reaction method, 5,6 although post annealing under the high-pressure oxygen of 10∼400 atm is indispensable to induce superconductivity.…”

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“…Thus, the STO substrate, which was used in the previous experiments, 3,4 is considered to be inappropriate for the growth of LCCO thin films. The c-axis length of the film on LAO is estimated to be ≈ 19.65 Å, which is longer than that of the film on LSAT (19.62 Å).…”

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confidence: 99%

In situepitaxial growth of superconducting La-based bilayer cuprate thin films

2004

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We investigate the epitaxial growth of bilayer cuprate La 2 CaCu 2 O 6+δ using pure ozone as an oxidant, and find that even the crystal with parent composition without cation substitution can show metallic behavior with the aid of epitaxial strain effect. The hole concentration is controlled simply by excess-oxygen doping, and the films grown under the optimum conditions exhibit superconductivity below 30 K. This is the first result on the superconductivity of bilayer La 2 CaCu 2 O 6+δ induced purely by the excess oxygen.1 Epitaxial growth technique is quite useful for the study of high-T c superconductors, because one can easily modify lattice parameters by choosing an appropriate substrate. In particular, La 2−x Sr x CuO 4 (LSCO) thin films can have higher T c than bulk crystals by adding in-plane compressive strain. 1,2 On the contrary to such a monolayer cuprate as LSCO, few results have been reported on the role of epitaxial strain in bilayer cuprates YBa 2 Cu 3 O 7 (YBCO) or Bi 2 Sr 2 CaCu 2 O 8 (BSCCO) so far, probably because no remarkable improvement of superconducting properties has been found in these compounds; Cu-O chain layers in YBCO or cleavable Bi-O layers in BSCCO may relax rapidly the lattice mismatch from the substrate in the initial growth stage. However, since bilayer cuprates show in general higher T c than monolayer ones, it would be fascinating if a remarkable T c enhancement is induced by the epitaxial strain. La 2−x (Sr,Ca) 1+x Cu 2 O 6+δ (La2126) is a good bilayer compound for the study of epitaxial growth, because this compound has a simpler crystal structure than YBCO and BSCCO. A few results on thin-film growth of La2126 on SrTiO 3 (100) have been reported, 3,4 but unfortunately superconducting films have never been obtained. As is widely known, La2126-type structure can be rather easily obtained by a conventional solid-state reaction method, 5,6 although post annealing under the high-pressure oxygen of 10∼400 atm is indispensable to induce superconductivity. 7,8 The results of Refs. 3 and 4 imply that their oxidation techniques were not efficient enough to oxidize the films as high-pressure oxygen does. Thus, one needs to develop a special technique to oxidize samples. One of the good candidates for oxidizing gas is pure ozone, because its handling techniques have been well established for more than a decade, 9,10 and have recently been applied to synthesize new superconductors such as Ba 2 CuO 4−δ and Sr 2 CuO 4−δ . 11,12 It has been reported that chemical activity of ozone is higher than that of molecular oxygen at GPa pressure, 13 although the life time of ozone at high temperatures is quite short (e.g., ∼10 0 s at 200 • C, and ∼10 −3 s at 500 • C). 14 In this paper we report a successful growth of superconducting La2126 thin films using pure ozone. In order to see the sole effect of oxidation by ozone, we concentrate on the parent composition, La 2 CaCu 2 O 6 (LCCO), in this report. A more-detailed account of the results for Sr and Ca substituted compounds will be described el...

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Molecular beam epitaxy and microstructural study of La2−xSr1+xCu
K. Verbist
¹
,
Ognjen Milat
²
,
Gustaaf Van Tendeloo
³

et al.

Cited by 2 publications

References 33 publications

Epitaxial Stabilization of Oxides in Thin Films

Epitaxial Stabilization of Oxides in Thin Films

In situepitaxial growth of superconducting La-based bilayer cuprate thin films

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Molecular beam epitaxy and microstructural study of La2−xSr1+xCuK. Verbist1, Ognjen Milat2, Gustaaf Van Tendeloo3 et al.

Cited by 2 publications

References 33 publications

Epitaxial Stabilization of Oxides in Thin Films

Epitaxial Stabilization of Oxides in Thin Films

In situepitaxial growth of superconducting La-based bilayer cuprate thin films

Contact Info

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Molecular beam epitaxy and microstructural study of La2−xSr1+xCu
K. Verbist
¹
,
Ognjen Milat
²
,
Gustaaf Van Tendeloo
³

et al.