Concomitant Magnetic Memory Effect in CrO₂–Cr₂O₃ Core–Shell Nanorods: Implications for Thermal Memory Devices

Abstract

The origin of the concomitant memory effect is still a controversial issue and poor evidence in the observation of nanocrystal systems. We report on a type of concomitant memory effect driven by first-field-induced unidirectional magnetic anisotropy at the interface of ferromagnetic CrO 2core and antiferromagnetic Cr 2 O 3 -shell nanorods, with the effect becoming less significant in pure CrO 2 nanorods. To corroborate the results, a core−shell anisotropic energy model was used to determine the coherent rotation of magnetization and exchange coupling constant, giving direct access to the anisotropic interfacial properties of the core−shell nanoscale system without spatially resolved magnetic measurement. The outcome of this study will be useful for the future development of thermal memory devices.

Magnetic Memory and the Promising Magnetocaloric Effect of Sn0.6Cr0.1Ge0.3Te Solid Solution Synthesized by Sealed Tube Solid-State Reaction

“…This temperature is known as the irreversible temperature ( T irr ), and for the Sn 0.6 Cr 0.1 Ge 0.3 Te sample, it was found to be 178 K. The T irr provides an insight into the sample’s SPM behavior. Each SPM cluster has its own blocking temperature T B , which is related to the magnetic anisotropy energy K eff and the volume V , according to the relationship K eff V ∝ k B T B , where k B is the Boltzmann constant . Thus, the particles become blocked at 132 K (blocking temperature) as the temperature gradually decreases below T irr .…”

“…where k B is the Boltzmann constant. 53 Thus, the particles become blocked at 132 K (blocking temperature) as the temperature gradually decreases below T irr . As the temperature further decreases below T B , the magnetization decreases, indicating the presence of a magnetic transition in the Sn 0.6 Cr 0.1 Ge 0.3 Te sample and the observation of a super SG state.…”

“…As the temperature further decreases below T B , the magnetization decreases, indicating the presence of a magnetic transition in the Sn 0.6 Cr 0.1 Ge 0.3 Te sample and the observation of a super SG state. 33,53,54 Further discussion on this topic is provided in the memory effect study.…”