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Growth of Laser Ablated YBa_{2}Cu_{3}O_{7} Thin Films Epitaxied on (100)MgO: Influence of In-Plane Misorientations on Low and High Frequency Properties

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Perrin A., Guilloux-Viry M., Castel X.

Acta Physica Polonica A

1997

vol. 92

issue 1

115-125

The graphoepitaxial growth of c-axis YBa_{2}Cu_{3}O_{7} laser ablated thin films on (100)MgO induces a competition between two main in-plane orientations due to the large lattice mismatch: ⟨100⟩ YBa_{2}Cu_{3}O_{7} ∥ ⟨100⟩ MgO, c_{⊥ 0} notation or ⟨110⟩ YBa_{2}Cu_{3}O_{7} ∥ ⟨100⟩ MgO, c_{⊥ 45} notation. The ratio of c_{⊥ 45}/c_{⊥ 0} in-plane orientations (η), measured by X-ray diffraction φ scans, is ranging from 0.2% to 49.7% for the films reported here. Their crystalline qualities were compared on the basis of rocking curves (Δθ), electron channeling patterns and reflection high energy electron diffraction diagrams. The coexistence of c_{⊥ 0} and c_{⊥ 45} domains creates high angle grain boundaries. No degradation of T_{c}, residual resistance ratio (RRR) or ΔT_{c} is observed when η increases. In contrast, a strong correlation between microwave losses characterized by surface resistance (R_{S} at 10 GHz and 77 K), inductive losses S(χ") (surface of the χ" peak obtained in a.c. susceptibility at 119 Hz) and η was clearly evidenced. A minimum of losses was found for η between 3 and 6% suggesting the necessity of a low quantity of high angle grain boundaries for films optimization. Finally, some specific processes carried out recently in order to try to efficiently control η, then R_{S} are discussed.

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1 Acta Physica Polonica A

1 1997

1 Castel X.

1 Guilloux-Viry M.

1 Perrin A.

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Growth of Laser Ablated YBa_{2}Cu_{3}O_{7} Thin Films Epitaxied on (100)MgO: Influence of In-Plane Misorientations on Low and High Frequency Properties