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Entangled core/shell magnetic structure driven by surface magnetic symmetry-breaking in Cr2O3 nanoparticles.

Authors :
Rinaldi-Montes, Natalia
Gorria, Pedro
Fuertes, Antonio B.
Martínez-Blanco, David
Amghouz, Zakariae
Puente-Orench, Inés
Olivi, Luca
Herrero-Martín, Javier
Fernandez-Garcia, Maria Paz
Alonso, Javier
Phan, Manh-Huong
Srikanth, Hariharan
Marti, Xavi
Blanco, Jesús A.
Source :
Journal of Materials Chemistry C; 2/7/2022, Vol. 10 Issue 5, p1798-1807, 10p
Publication Year :
2022

Abstract

Bulk Cr<subscript>2</subscript>O<subscript>3</subscript> is an antiferromagnetic (AFM) oxide that exhibits the magnetoelectric effect at room temperature, with neither spontaneous magnetization nor net electric polarization. These physical properties stem from a subtle competition between exchange and crystal field interactions. In this article, we exploit the symmetry breaking at the surface of Cr<subscript>2</subscript>O<subscript>3</subscript> nanoparticles for unbalancing this delicate physical equilibrium. The emerging weak ferromagnetic signal we observe persists up to near room temperature (≈ 270 K) at which the antiferromagnetic order disappears. In addition, an exchange-bias effect, that rapidly decreases on heating from low temperature up to 30 K, is resistant to thermal disorder above 200 K. Our findings point to the possible formation of an entangled core/shell magnetic structure, where pinned uncompensated spins at the shell are randomly distributed in a low-temperature spin-glass ordering, with low net magnetic moment and an ordering temperature governed by the AFM Néel temperature. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
20507526
Volume :
10
Issue :
5
Database :
Complementary Index
Journal :
Journal of Materials Chemistry C
Publication Type :
Academic Journal
Accession number :
155052317
Full Text :
https://doi.org/10.1039/d1tc04947j