Flux pinning mechanisms in ErNi2B2C - art. no. 092512

We present local Hall probe measurements of the superconducting and magneti cally ordered material ErNi2B2C (T-c similar or equal to 10.5 K, T-N simila r or equal to 6 K). The onset of incommensurate antiferromagnetic order at T-N, within the superconducting state, results in an increase in vortex pin ning for B parallel toc. For B perpendicular toc no increase in pinning is observed at T-N, consistent with the notion of vortex pinning by planar mag netic domain boundaries for B parallel toc. The development of a weak ferro magnetic component below T-wf similar or equal to 2.5 K results in a furthe r increase in pinning for both orientations, suggesting that a different me chanism is responsible for this second increase at lower temperatures.