Room-temperature exchange bias from antiphase boundary induced exchange frustration in single-phase Fe3O4

This is the authors' abstract. We don't add key points for this paper.

Room-temperature exchange bias (EB) is realized in single-phase ferrimagnetic Fe 3 O 4 nanoparticle agglomerates without the presence of conventional ferromagnetic/antiferromagnetic heterointerfaces. Magnetic measurements reveal a pronounced and stable loop shift at 300 K. High-resolution structural characterization directly identifies antiphase boundaries (APBs) as the dominant crystallographic defects within the Fe 3 O 4 nanoparticles. Temperature-dependent hysteresis loops further show that the loop displacement progressively decreases with increasing temperature, remains discernible up to 850 K, and approaches zero at 900 K, defining the high-temperature stability window of APB-mediated pinning. These defects locally disrupt cation ordering, induce frustrated exchange interactions, and generate antiferromagnetic-like spin configurations that act as nanoscale pinning centers. The resulting defect-induced exchange anisotropy produces a robust EB within an otherwise homogeneous ferrimagnetic matrix. The findings highlight APBs as functional magnetic building blocks and provide a scalable pathway toward interface-free exchange-biased spintronic materials operating at room temperature.