arXiv subjects

S. Gaudio

Publications and source records attributed to S. Gaudio.

3 recordsLinked to original sources

arXiv2008

Finite size Berezinski-Kosterlitz-Thouless transition at grain boundaries in solid $^4$He and role of $^3$He impurities

We analyze the complex phenomenology of the Non-Classical Rotational Inertia (NCRI) observed at low temperature in solid $^4$He within the context of a two dimensional Berezinski-Kosterlitz-Thouless transition in a premelted $^4$He film at the grain boundaries. We show that both the temperature and $^3$He doping dependence of the NCRI fraction (NCRIF) can be ascribed to finite size effects induced by the finite grain size. We give an estimate of the average size of the grains which we argue to be limited by the isotopic $^3$He impurities and we provide a simple power-law relation between the NCRIF and the $^3$He concentration.

cond-mat.other↗

arXiv2008

Spin Collective Modes of Two-Species Fermi Liquids: Helium-3 and Atomic Gases near the Feshbach Resonance

We present theoretical findings on the spin collective modes of a two-species Fermi liquid, prepared alternatively in a polarized equilibrium or a polarized non-equilibrium state. We explore the effects on these modes of a diverging s-wave scattering length, as occurs near a Feshbach resonance in a Fermionic atomic gas. We compare these atomic gas modes with those of the conventional Helium-3 system, and we find that they differ from the conventional systems, and that the gap and spin stiffness are tunable via the Feshbach resonance.

cond-mat.other↗

arXiv2007

Surface instability and isotopic impurities in quantum solids

In this paper we employ a self-consistent harmonic approximation to investigate surface melting and local melting close to quantum impurities in quantum solids. We show that surface melting can occur at temperatures much lower than the critical temperature $T_c$ of the solid phase instability in the bulk. Similar effects are driven by the presence of an isotope substitution. In this latter case, we show that stronger local lattice fluctuations, induced by a lighter isotope atom, can induce local melting of the host bulk phase. Experimental consequences and the possible relevance in solid helium are discussed.

cond-mat.stat-mech↗