Exchange bias in gap-free ferromagnetic/antiferromagnet heterostructures under zero-field-cooling

Abstract

The exchange bias (EB) effect, a ubiquitous phenomenon at ferromagnetic/antiferromagnetic interfaces, plays a pivotal role in advancing high-sensitivity magnetic data storage and high-density spintronic devices. However, its pronounced sensitivity to interfacial environmental factors, such as lattice mismatch, contamination, and thermal fluctuations, has hindered scalable device fabrication and performance optimization. We employ a one-pot chemical vapor deposition strategy to synthesize Cr2Te3/Cr2O3 vertical heterostructures (VHS) with atomically sharp interfaces. The formation of Cr–O–Te covalent bonds at the heterointerface ensures crystallinity and thermal stability, establishing an ideal platform for robust EB effects. Remarkably, interfacial charge transfer between Cr2Te3 and Cr2O3 induces near-room-temperature ferromagnetic ordering in Cr2O3, with a Curie temperature (TC) of 282 K. First-principles calculations reveal a charge transfer of approximately 0.22 electrons from each Cr2O3 to Cr2Te3, resulting in the emergence of interfacial ferromagnetism. Notably, the Cr2Te3/Cr2O3 VHS exhibits stable ferromagnetic behavior with a coercive field (HC) of 28 mT at 200 K, exceeding the operational limits of pristine Cr2Te3. At 80 K, a significant exchange bias field (HEB) of 61 mT is observed under zero-field-cooling, unequivocally demonstrating a strong interfacial spin-pinning effect. This study establishes an efficient platform for exploring strong EB effects in two-dimensional magnetic heterostructures by engineering interfacial charge transfer and spin-pinning interactions, paving the way for room-temperature spintronic systems with enhanced operational stability and scalability.