A temperature-dependent switching of the exchange bias effect from negative to positive under a fixed intermediate cooling field

Abstract

An interfacial coupling origin of the exchange bias effect (EBE) is a novel phenomenon due to its technological and fundamental importance.

Connection Between Intrinsic Interfacial Frozen Spins and Exchange Bias Effect in Core@Shell Iron@Iron‐Oxide Nanoparticles

“…This indicates that a strong exchange coupling appears at the interface between the core (Fe) and shell (Fe‐oxide). [ 9,50,51 ] The details can be observed in the enlarged view of the hysteresis loop in Figure 4b. In contrast, the shift in the hysteresis loop disappears under the ZFC condition, where the coercivity also decreases from 1590 to 363 Oe.…”

An Investigation of Inverted Core@Shell Nanostructure for Efficacious Magnetic Hyperthermia Applications

“…Depending on the nature of the applied cooling field and its spin orientation at the CS interface, EBE may result in negative (ferromagnetic spin arrangement) or positive (antiferromagnetic spin arrangement) shifting. [ 16 ] The revelation of frustrated uncompensated spins at the CS interface, particularly for AF/F or F/AF systems, is well authenticated through experimental and theoretical study as well. It is well understood that the coercivity amplification is in regard to the uncompensated spins at the interface, which are not pinned to F spins and usually experience an additional torque from the F spins in an attempt to orient the spins along its direction, and the number of uncompensated AF spins pinned to F spins at the junction interface give in to shift of the hysteresis loop.…”

“…The sample production of CS N@F used a two‐pace coprecipitation approach prescribed in another study. [ 16 ] 1.975 g of NiCl 2 ·6H 2 O was mixed in a Milli Q water of 50 mL to achieve suitable molar concentrations. A solution of NaOH (1.125 g) with 10 mL Milli Q water was appended drop wise when the mixture was muddled magnetically for 30 min at 50 °C maintaining a pH of 12.…”

“…Also, it is important to mark that the Curie temperature (T C ) is lofty over Neel's temperature (T N ) for such a CS system. [15][16][17] The reverse version of normal-type CS devises a single inverted CS system, meaning that the core element is merged with AF material, while the shell element consists of F material. However, T C and T N requirements for a single inverted CS are identical to that of normal CS order.…”