Intermittent superconductivity and unconventional vortex configurations in nanoscale superconducting noncircular systems

•The flux-dependent evolution of vortex states in small superconducting nanosquares is investigated.•The spatial variations of the superconducting order parameter are very sensitive to the finite size of the sample.•A remarkable intermittent superconducting behavior for the ground-state transition is found.•The asymmetric single-vortex and multivortex states as well as the vortex-antivortex pairs can emerge as the metastable or ground states.