Angular stripe phase in spin-orbital-angular-momentum coupled Bose condensates

We propose that a superfluid with supersolidlike properties, i.e., angular stripe phase, can be realized in a pancakelike spin-1/2 Bose gas with spin-orbital-angular-momentum coupling. We predict a rich ground-state phase diagram, including the vortex-antivortex pair phase, the half-skyrmion phase, and two different angular stripe phases. The stripe phases feature a modulated angular density-density correlation with a sizable contrast and can occupy a relatively large parameter space. The low-lying collective excitations, such as the dipole and breathing modes, show distinct behaviors in different phases. The existence of the stripe phase is also clearly indicated in the energetic and dynamic instabilities of collective modes near phase transitions. Our predictions of the angular stripe phase could be readily examined in current cold-atom experiments with 87Rb and 41K.