Perfect Domain-Lattice Matching between MgB₂and Al₂O₃: Single-Crystal MgB₂Thin Films Grown on Sapphire

Abstract

A comprehensive analysis of gened relativistic spacetimes which admit a shearfree, irrotational and geodesic time-like coogruence is presented. The equations governing the models for a gened energy-momentum tensor are wrilten down. Coordinates in which the metric of such spacetimes takes on a simplified form are established. The general subwses of 'zero anisotropic stress', 'zero heat-flux vector' and 'two-component Ruids' are investigated. In particular, perfect-fluid Friedmann-Robertson-Walker models and spatially homogeneous models are discussed. Models with a variety of physically relevant energy-momentum tensors are considered. Anisowopic fluid models and viscous fluid models with heat conduction are examined. Also. models with B perfect Ruid plus a magnetic field or with pure radiation. and models with two non-collinw perfect fluids (satisfying a variety of physical conditions) are inwtigated. In particular. models with a (single) perfect Ruid which is tilting with respect to the shem-free, vorticity-free and acceleration-free time-like congruence are discussed.PACS numbers: 0420J. 9880H

Influence of carbon-ion irradiation on the superconducting critical properties of MgB2 thin films

“…High-quality MgB 2 thin films of thicknesses 400 nm (MB400nm) and 800 nm (MB800nm) were fabricated on c-cut Al 2 O 3 substrates for C-ion irradiation studies by using a hybrid physicalchemical vapor deposition method, the details of the growth technique were described earlier [28,29]. C-ion irradiation was carried out using Cockcroft-Walton type 400 kV ion beam accelerator at Korea Institute of Science and Technology (KIST), Seoul.…”

Effects of irradiation on superconducting properties of small-grained MgB2 thin films

“…The c-axis-oriented MgB 2 thin films with grain sizes of approximately 122 nm and 140 nm were fabricated using a hybrid physical-chemical vapor deposition (HPCVD) system, and the details of the fabrication condition and quality of films were described everywhere. [24][25][26] The c-cut Al 2 O 3 substrate of 10 mm×10 mm in size was placed on the susceptor filled with 99.99% purity Mg pieces. The carrier gas was H 2 at a flow rate of 80 sccm, and the susceptor was heated to 700 • C in a total pressure of 100 Torr (1 Torr = 1.33322×10 2 Pa).…”

Influence of disorder strength on the superconducting mechanism of MgB2

“…The highly c-axis-oriented MgB 2 thin films were fabricated on c-cut Al 2 O 3 substrates by a hybrid physical-chemical vapor deposition system [22,23]. The Al 2 O 3 substrate of 10 × 10 mm 2 in size was placed on the susceptor filled with 99.99% purity Mg pieces.…”