Little-Parks oscillation and ${\bf d}$-vector texture in spin-triplet superconducting rings with bias current

We theoretically investigate the critical bias current $j_c$ for a superconducting (SC) ring in a magnetic field. Based on the Ginzburg-Landau theory, we show that $j_c$ exhibits a Little-Parks (LP) oscillation as a function of the magnetic flux passing through the ring, similarly to the LP oscillation in the SC transition temperature. It is also found that for a spin-triplet SC ring, the ${\bf d}$-vector rotates to yield a larger $j_c$, forming a texture along the circumference of the ring. Experimental implications of our result are discussed.