Ferroelectricity-Induced Surface Ferromagnetism in Core-Shell Magnetoelectric Nanoparticles

abstract

Magnetoelectric nanoparticles (NPs) present an important class of nanomaterials with a wide interest in piezocatalytic and biomedical applications. Herein, the results of magnetoelectric and magnetization measurements performed on core-shell NPs having magnetic core (MnFe2O4, MFO) and ferroelectric shell (Ba0.85Ca0.15Ti0.5Zr0.5O3, BCZT) synthesized by the microwave hydrothermal method are reported. Magnetic results are compared with the measurements on reference MFO NPs prepared under identical conditions. Detailed SQUID magnetometer measurements of the magnetization hysteresis loops M(H) down to 2 K reveal the existence of a clear exchange bias effect in pure MFO NPs attributed to the coexistence of ferromagnetic and antiferromagnetic short-range interactions. When the magnetic core is covered by the thin ferroelectric BCZT shell, it is observed that 1) the shell suppresses the apparent bias effect and 2) induces an "extra" ferromagnetic magnetization at T < 20 K. The results indicate that this "extra" ferromagnetism has a 2D character and it is most likely related to the interface interactions between the MFO core and BCZT shell. Ferroelectric properties and strong magnetoelectric effect in core-shell NPs are revealed via piezoresponse force microscopy under magnetic field. The mechanisms of the observed effects are discussed.

keywords

MAGNETIC-PROPERTIES; DELIVERY

subject category

Materials Science; Physics

authors

Canhassi, CAI; Chernozem, RV; Chernozem, PV; Romanyuk, KN; Zelenovskiy, P; Urakova, AO; Gerasimov, EY; Koptsev, DA; Surmeneva, MA; Surmenev, RA; Kholkin, AL; Kopelevich, Y

Groups

G2 - Photonic, Electronic and Magnetic Materials
G3 - Electrochemical Materials, Interfaces and Coatings

Projects

CICECO - Aveiro Institute of Materials (UIDB/50011/2020)

CICECO - Aveiro Institute of Materials (UIDP/50011/2020)

Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)

Photo-responsive organic-inorganic hybrid multiferroics: A way toward multifunctional electronics (PTDC/CTM-CTM/4044/2020)

acknowledgements

This work was financially supported by the Russian Science Foundation (project no. 24-43-00171: morphology, composition, and structure analysis) and Ministry of Science and Higher Education (#075-15-2021-588 of June 1, 2021: materials and sample fabrication). Part of the work (AFM and MFM) was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 (DOI 10.54499/UIDB/50011/2020), UIDP/50011/2020 (DOI 10.54499/UIDP/50011/2020) & LA/P/0006/2020 (DOI 10.54499/LA/P/0006/2020), financed by national funds through the FCT/MCTES (PIDDAC). K.N.R., P.Z., and A.L.K. wish to thank FCT for funding through the project PTDC/CTM-CTM/4044/2020. C.A.I.C. and Y.K. were supported by CNPq and FAPESP (Brazilian scientific agencies). K.N.R. was also funded by National Funds (OE), through FCT, I.P., in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of the Article 23, of the Decree-Law57/2016, of August 29, changed by Law 57/2017, of July 19. The authors thank the central laboratories of Tomsk Polytechnic University (Analytical Centre) for the XPS measurements.