Magnetic Proximity Effect Features in Antiferromagnetic/Ferrimagnetic Core-Shell Nanoparticles

Phys. Rev. Lett. 102, 247201 (2009)

URL:

http://link.aps.org/doi/10.1103/PhysRevLett.102.247201

I. V. Golosovsky, G. Salazar-Alvarez, A. López-Ortega, M. A. González, J. Sort, M. Estrader, S. Suriñach, M. D. Baró, and J. Nogués DOI:

10.1103/PhysRevLett.102.247201

Abstract:
A study of “inverted” core-shell, MnO/γ-Mn₂O₃, nanoparticles is presented. Crystal and magnetic structures and characteristic sizes have been determined by neutron diffraction for the antiferromagnetic core (MnO) and the ferrimagnetic shell (γ-Mn₂O₃). Remarkably, while the MnO core is found to have a T_N not far from its bulk value, the magnetic order of the γ-Mn₂O₃ shell is stable far above T_C, exhibiting two characteristic temperatures, at T∼40  K [T_C(γ-Mn₂O₃)] and at T∼120  K [∼T_N(MnO)]. Magnetization measurements are consistent with these results. The stabilization of the shell moment up to T_N of the core can be tentatively attributed to core-shell exchange interactions, hinting at a possible magnetic proximity effect.