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Papers by pippo carlo

Research paper thumbnail of Josephson coupling between superconducting islands on single and bilayer graphene

We study the Josephson coupling of superconducting (SC) islands through the surface of single-lay... more We study the Josephson coupling of superconducting (SC) islands through the surface of single-layer (SLG) and bilayer (BLG) graphene in the long-junction regime, as a function of the distance between the grains, temperature, chemical potential and external (transverse) gate-voltage. For SLG, we provide a comparison with existing literature. The proximity effect is analyzed through a Matsubara Green's function approach. This represents the first step in a discussion of the conditions for the onset of a granular superconductivity within the film, made possible by Josephson currents flowing between superconductors. To ensure phase coherence over the 2D sample, a random spatial distribution can be assumed for the SC islands on the SLG sheet (or intercalating the BLG sheets). The tunable gatevoltage-induced band gap of BLG affects the asymptotic decay of the Josephson coupling-distance characteristic for each pair of SC islands in the sample, which results in a qualitatively strong field dependence of the relation between Berezinskii-Kosterlitz-Thouless transition critical temperature and gate voltage.

Research paper thumbnail of BKT transition for bilayer graphene-based granular superconductors

Bulletin of the American Physical Society, 2014

Research paper thumbnail of Surface tension and the Mori–Tanaka theory of non-dilute soft composite solids

Proceedings of the Royal Society A: Mathematical, Physical and Engineering Science, 2016

Eshelby's theory is the foundation of composite mechanics, allowing calculation of the effect... more Eshelby's theory is the foundation of composite mechanics, allowing calculation of the effective elastic moduli of composites from a knowledge of their microstructure. However, it ignores interfacial stress and only applies to very dilute composites—i.e. where any inclusions are widely spaced apart. Here, within the framework of the Mori–Tanaka multiphase approximation scheme, we extend Eshelby's theory to treat a composite with interfacial stress in the non-dilute limit. In particular, we calculate the elastic moduli of composites comprised of a compliant, elastic solid hosting a non-dilute distribution of identical liquid droplets. The composite stiffness depends strongly on the ratio of the droplet size, R , to an elastocapillary lengthscale, L . Interfacial tension substantially impacts the effective elastic moduli of the composite when R / L ≲ 100 . When R <3 L /2 ( R =3 L /2) liquid inclusions stiffen (cloak the far-field signature of) the solid.

Research paper thumbnail of Josephson coupling between superconducting islands on single and bilayer graphene

We study the Josephson coupling of superconducting (SC) islands through the surface of single-lay... more We study the Josephson coupling of superconducting (SC) islands through the surface of single-layer (SLG) and bilayer (BLG) graphene in the long-junction regime, as a function of the distance between the grains, temperature, chemical potential and external (transverse) gate-voltage. For SLG, we provide a comparison with existing literature. The proximity effect is analyzed through a Matsubara Green's function approach. This represents the first step in a discussion of the conditions for the onset of a granular superconductivity within the film, made possible by Josephson currents flowing between superconductors. To ensure phase coherence over the 2D sample, a random spatial distribution can be assumed for the SC islands on the SLG sheet (or intercalating the BLG sheets). The tunable gatevoltage-induced band gap of BLG affects the asymptotic decay of the Josephson coupling-distance characteristic for each pair of SC islands in the sample, which results in a qualitatively strong field dependence of the relation between Berezinskii-Kosterlitz-Thouless transition critical temperature and gate voltage.

Research paper thumbnail of BKT transition for bilayer graphene-based granular superconductors

Bulletin of the American Physical Society, 2014

Research paper thumbnail of Surface tension and the Mori–Tanaka theory of non-dilute soft composite solids

Proceedings of the Royal Society A: Mathematical, Physical and Engineering Science, 2016

Eshelby's theory is the foundation of composite mechanics, allowing calculation of the effect... more Eshelby's theory is the foundation of composite mechanics, allowing calculation of the effective elastic moduli of composites from a knowledge of their microstructure. However, it ignores interfacial stress and only applies to very dilute composites—i.e. where any inclusions are widely spaced apart. Here, within the framework of the Mori–Tanaka multiphase approximation scheme, we extend Eshelby's theory to treat a composite with interfacial stress in the non-dilute limit. In particular, we calculate the elastic moduli of composites comprised of a compliant, elastic solid hosting a non-dilute distribution of identical liquid droplets. The composite stiffness depends strongly on the ratio of the droplet size, R , to an elastocapillary lengthscale, L . Interfacial tension substantially impacts the effective elastic moduli of the composite when R / L ≲ 100 . When R <3 L /2 ( R =3 L /2) liquid inclusions stiffen (cloak the far-field signature of) the solid.

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