S G Söyler

Abdus Salam International Centre for Theoretical Physics, Trst, Friuli Venezia Giulia, Italy

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Publications (3)15.46 Total impact

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    ABSTRACT: We establish the full ground state phase diagram of the disordered Bose-Hubbard model in two dimensions at a unity filling factor via quantum Monte Carlo simulations. Similarly to the three-dimensional case we observe extended superfluid regions persisting up to extremely large values of disorder and interaction strength which, however, have small superfluid fractions and thus low transition temperatures. In the vicinity of the superfluid-insulator transition of the pure system, we observe an unexpectedly weak--almost not resolvable--sensitivity of the critical interaction to the strength of (weak) disorder.
    Physical Review Letters 10/2011; 107(18):185301. · 7.73 Impact Factor
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    ABSTRACT: In the experiment on superfluid transport in solid He4 [PRL 100, 235301 (2008)], Ray and Hallock observed an anomalously large isochoric compressibility: the supersolid samples demonstrated a significant and apparently spatially uniform response of density and pressure to chemical potential mu, applied locally through Vycor ``electrodes.'' We propose that the effect is due to superclimb: edge dislocations can climb because of mass transport along superfluid cores and, as a result, the crystal can accumulate extra matter which is, practically, independent of the dislocation density, provided it is uniform. We corroborate this scenario by ab initio simulations of an edge dislocation in solid He4 at T=0.5K with Burgers vector along the C-axis: its superfluid core (split into partials) climbed in response to changes of mu [1]. At low T the effect must be suppressed due to a crossover to the smooth dislocation, with the temperature scale determined by the energy of jog-antijog pair. [4pt] [1] S.G. S"oyler, A. B. Kuklov, L. Pollet, N. V. Prokof'ev, and B. V. Svistunov , Phys. Rev. Lett. 103, 175301 (2009).
    03/2010;
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    ABSTRACT: In the experiment on superfluid transport in solid 4He [Phys. Rev. Lett. 100, 235301 (2008)], Ray and Hallock observed an anomalously large isochoric compressibility: the supersolid samples demonstrated a significant and apparently spatially uniform response of density and pressure to chemical potential, applied locally through Vycor "electrodes." We propose that the effect is due to superclimb: edge dislocations can climb because of mass transport along superfluid cores. We corroborate the scenario by ab initio simulations of an edge dislocation in solid 4He at T = 0.5 K. We argue that at low temperature the effect must be suppressed due to a crossover to the smooth dislocation.
    Physical Review Letters 10/2009; 103(17):175301. · 7.73 Impact Factor