Magnetic proximity effect features in antiferromagnetic/ferrimagnetic core-shell nanoparticles

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Core-shell nanoparticles offer tunable properties.
• Understanding interfacial magnetic effects is crucial for advanced materials.

Purpose of the Study:

• To investigate the crystal and magnetic structures of "inverted" MnO/gamma-Mn(2)O(3) core-shell nanoparticles.
• To explore the magnetic behavior and characteristic temperatures of the antiferromagnetic core and ferrimagnetic shell.
• To elucidate the influence of core-shell interactions on magnetic ordering.

Main Methods:

• Neutron diffraction was employed to determine crystal and magnetic structures and characteristic sizes.
• Magnetization measurements were conducted to corroborate structural findings.

Main Results:

• Neutron diffraction confirmed the antiferromagnetic nature of the MnO core and the ferrimagnetic nature of the gamma-Mn(2)O(3) shell.
• The magnetic order of the gamma-Mn(2)O(3) shell remained stable significantly above its bulk critical temperature (T_{C}).
• Two characteristic temperatures were observed for the shell: approximately 40 K (T_{C} of gamma-Mn(2)O(3)) and approximately 120 K (near T_{N} of MnO).

Conclusions:

• The magnetic order of the shell is stabilized up to the Néel temperature (T_{N}) of the core.
• Core-shell exchange interactions are tentatively attributed to the stabilization of the shell moment.
• The findings suggest a potential magnetic proximity effect at the core-shell interface.