We experimentally study magnetization aging in a thin-film NiO/permalloy bilayer. Aging characteristics are nearly independent of temperature below the exchange bias blocking temperature $T_B$, but rapidly vary above it. The dependence on the magnetic history qualitatively changes across $T_B$. The observed behaviors are consistent with the spin glass transition at $T_B$, with significant implications for magnetism and magnetoelectronic phenomena in antiferromagnet/ferromagnet bilayers.

• Received 30 November 2017
• Revised 19 January 2018

DOI:https://doi.org/10.1103/PhysRevB.97.054402