Half-quantum flux in spin-triplet superconducting rings with bias current

Effects of a bias electric current have been theoretically investigated in a spin-triplet superconducting ring in a magnetic field. Based on the Ginzburg-Landau theory, we show that the bias current can stabilize a half-quantum-flux (HQF) state via couplings to the Zeeman field and the dipole-type spin-orbit interaction, the latter becoming active when the field is tilted from the ring axis. The emergence of the HQF state is reflected as a field-induced half-quantum-shift in the Little-Parks (LP) oscillation in the critical current. Possible relevance to recent LP experiments is also discussed.