Systematic study of disorder induced by neutron irradiation in MgB2 thin films

Abstract

The effects of neutron irradiation on normal state and superconducting properties of epitaxial magnesium diboride thin films are studied up to fluences of 1020 cm-2. All the properties of the films change systematically upon irradiation. Critical temperature is suppressed and, at the highest fluence, no superconducting transition is observed down to 1.8 K. Residual resistivity progressively increases from 1 to 190 microohmcm; c axis expands and then saturates at the highest damage level. We discuss the mechanism of damage through the comparison with other damage procedures. The normal state magnetoresistivity of selected samples measured up to high fields (28 and 45T) allows to determine unambiguously the scattering rates in each band; the crossover between the clean and dirty limit in each sample can be monitored. This set of samples, with controlled amount of disorder, is suitable to study the puzzling problem of critical field in magnesium diboride thin films. The measured critical field values are extremely high (of the order of 50T in the parallel direction at low fluences) and turns out to be rather independent on the experimental resistivity, at least at low fluences. A simple model to explain this phenomenology is presented.

29 pages, 6 figures, accepted for publication on J. of Applied Physics

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Cited by in corpus (6)

• Fully Band Resolved Scattering Rate in MgB2 Revealed by Nonlinear Hall Effect and Magnetoresistance Measurements
• Two-band parallel conductivity at terahertz frequencies in the superconducting state of MgB${}_2$.
• First critical field measurements of superconducting films by third harmonic analysis
• Probing the electron-phonon coupling in MgB2 through magnetoresistance measurements in neutron irradiated thin films
• Influence of carbon-ion irradiation on the superconducting critical properties of MgB${}_2$ thin films
• Roles of intrinsic anisotropy and pi-band pairbreaking effects on critical currents in tilted c-axis MgB2 films probed by magneto-optical and transport measurements