Magnetic relaxation phenomena in cobalt

Abstract

The magnetic relaxation spectrum of polycrystalline, unirradiated Co has been investigated from 4 to 700 K. Both polycrystalline and single-crystal hexagonal close-packed Co have also been investigated after 3 MeV electron irradiation at either 8 or 40 K to doses of 1023 m–2. For unirradiated Co, results are interpreted as due to interactions between dislocations and domain walls. After irradiation at 8 K, relaxation peaks occur in the range 10 –50 K due to the re-orientation of Frenkel pairs which stabilise at the start of the stage-I anneal; a relaxation at 75 K is attributed to an intrinsic interstitial trapped at interstitial carbon. On anneal in the range 220 – 400 K, low-temperature relaxations evolve in samples containing impurities; these are attributed to reorientation of the migrating stage-III defects trapped at impurities.