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Epitaxially Induced Defects in Sr- and O-doped La_{2}CuO_{4} Thin Films Grown by MBE: Implications for Transport Properties

100%

Locquet J., Williams E.

Acta Physica Polonica A

1997

vol. 92

issue 1

69-84

In this paper, the critical role played by various types of defects and strain relaxation mechanisms in high-T_{c} thin films is highlighted and illustrated with examples. The defects are essential for providing adequate diffusion channels for oxygen ingress during the cooling step in c-axis thin films. The operation of strain relaxation mechanisms necessitated by the lattice mismatch between film and substrate can impose a compressive or tensile biaxial pressure, which either increases or reduces the critical temperature.

Anharmonicity and Weak Mode Assignment in La_{2-x}Sr_xCuO_4, with Oxygen Isotopic Substitution

100%

Siranidi E., Lampakis D., Palles D., Liarokapis E., Conder K.

Acta Physica Polonica A

2007

vol. 111

issue 1

173-177

The oxygen isotope effect on the first- and second-order Raman active modes of high-quality La_{2-x}Sr_xCu^{16,18}O_4 (80% substitution ^{16}O by ^{18}O) polycrystalline compounds with x=0.00, 0.015 was investigated at low temperatures. In the second-order Raman scattering several weak and strong peaks were observed and assigned to oxygen atom vibrations. With the isotopic substitution the apex oxygen mode follows quite well the mass harmonic law at all temperatures studied, while the soft mode is anharmonic in the temperature range of 77-180 K and for higher temperatures its anharmonicity is strongly increased. The temperature dependence of the energy of the soft mode for x=0.0 shows also a modification at≈180 K and an abnormal behaviour at≈280 K, which may be related with the transition to the antiferromagnetic phase.

Strain Relaxation in Thin Films of La_{1.85}Sr_{0.15}CuO_4 Grown by Pulsed Laser Deposition

88%

Zaytseva I., Cieplak M., Abal'oshev A., Berkowski M., Domukhovski V., Paszkowicz W., Shalimov A.

Acta Physica Polonica A

2007

vol. 111

issue 1

185-188

X-ray diffraction, resistivity, and susceptibility measurements are used to examine the effects of film thickness d (from 17 to 250 nm) on the structural and superconducting properties of La_{1.85}Sr_{0.15}CuO_4 films grown by pulsed laser deposition on SrLaAlO_4 substrates. For each d the film sgrow with a variable strain, ranging from a large compressive strain in the thinnest films to a negligible or tensile strain in thick films. Our results indicate that the tensile strain is not caused by the off-stoichiometric layer at the substrate-film interface. Instead, it may be caused by the extreme oxygen deficiency in some of the films.

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3 Acta Physica Polonica A

2 2007

1 1997

1 Abal'oshev A.

1 Berkowski M.

1 Cieplak M.

1 Conder K.

1 Domukhovski V.

1 Lampakis D.

1 Liarokapis E.

1 Locquet J.

1 Palles D.

1 Paszkowicz W.

1 Shalimov A.

1 Siranidi E.

1 Williams E.

1 Zaytseva I.

Search results

Epitaxially Induced Defects in Sr- and O-doped La_{2}CuO_{4} Thin Films Grown by MBE: Implications for Transport Properties

Anharmonicity and Weak Mode Assignment in La_{2-x}Sr_xCuO_4, with Oxygen Isotopic Substitution

Strain Relaxation in Thin Films of La_{1.85}Sr_{0.15}CuO_4 Grown by Pulsed Laser Deposition