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Appl. Phys. Lett. 103, 112601 (2013).
A. M. Awasthi, S. Bhardwaj, V. P. S. Awana, A. Figini Albisetti, G. Giunchi, A. V. Narlikar
UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 001, India and
National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110 012, India and
EDISON S.p.A., R&D Department, Foro Buonaparte 31, I-20121 Milano, Italy.
Abstract
Anisotropic-gap and two-band effects smear out the superconducting transition (T c) in literature reported thermal conductivity of MgB2, where large electronic contributions also suppress anomaly-manifestation in their negligible phononic-parts. Present thermal transportresults on scarcely explored specimens featuring nano-inclusions exhibit a small but clear T c-signature, traced to relatively appreciable phononic conduction, and its dominant electronic-scattering. The self-formed MgO as extended defects strongly scatter the charge carriers and minutely the phonons with their longer-mean-free-path near T c. Conversely, near room temperature, the shorter-dominant-wavelength phonon’s transport is hugely affected by these nanoparticles, undergoing ballistic to diffusive crossover and eventually entering the Ioffe-Regel mobility threshold regime.
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