Supersolid Research Articles

Supersolid Flow in Grain Boundaries?

Supersolid Flow in Grain Boundaries?

In search of 4He supersolid

In search of 4He supersolid

Super solids: new coatings technology from DuPont

Super solids: new coatings technology from DuPont

Supersolid phase in fully frustrated Josephson-junction arrays

We study the phase diagram and the excitation spectra of an array of small Josephson junctions at $f=1/2$ and arbitrary charge frustration. We find that the supersolid region in the phase diagram is larger than the correspondent region at $f=0$ and it includes two different phases.In the chiral supersolid (SS) charges and vortices are arranged in a checkerboard pattern on a $2\:\times \:2$ supercell analogously to the unfrustrated case. We find a new phase, which we term {\em non-chiral supersolid} (NCSS), which has no corresponding phase at $f=0$. The excitation spectra in the supersolid regions show particle like dispersions which is related to the defectons. The defecton condensation leads to superfluidity in the presence of charge ordered background.

Critical behavior of the supersolid transition in Bose-Hubbard models

We study the phase transitions of interacting bosons at zero temperature between superfluid (SF) and supersolid (SS) states. The latter are characterized by simultaneous off-diagonal long-range order and broken translational symmetry. The critical phenomena is described by a long-wavelength effective action, derived on symmetry grounds and verified by explicit calculation. We consider two types of supersolid ordering: checkerboard (X) and collinear (C), which are the simplest cases arising in two dimensions on a square lattice. We find that the SF--CSS transition is in the three-dimensional XY universality class. The SF--XSS transition exhibits non-trivial new critical behavior, and appears, within a $d=3-\epsilon$ expansion to be driven generically first order by fluctuations. However, within a one--loop calculation directly in $d=2$ a strong coupling fixed point with striking ``non-Bose liquid'' behavior is found. At special isolated multi-critical points of particle-hole symmetry, the system falls into the 3d Ising universality class.