Abstract
In superconductors, the condensation of Cooper pairs gives rise to fluxoid quantization in discrete units of Φ₀ = hc / 2e. The denominator of 2e is the signature of electron pairing, which is evidenced by a number of macroscopic quantum phenomena, such as the Little-Parks effect and the Josephson effect, where the critical temperature or the critical current oscillates in the period of Φ₀. Here we report the observation of fractional Little-Parks effect in mesoscopic rings of epitaxial β-Bi₂Pd, a topological superconductor. Besides Φ₀, novel Little-Parks oscillation periodicities of 2Φ₀, 3Φ₀ and 4Φ₀ are also observed, implying quasiparticles with effective charges being a fraction of a Cooper pair. We show that the fractional Little-Parks effect may be closely related to the fractional Josephson effect, which is a key signature of chiral Majorana edge states.