Nanoscale magnetization inhomogeneity within single phase nanopillars

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Multiferroic heterostructures offer unique functionalities by combining different material properties.
• Epitaxially strained cobalt ferrite (CoFe2O4) nanopillars in a barium titanate (BaTiO3) matrix exhibit self-assembling three-dimensional architectures.
• Understanding magnetic anisotropy is crucial for developing advanced electronic devices.

Purpose of the Study:

• To investigate the radial dependence of magnetic anisotropy in CoFe2O4 nanopillars within a BaTiO3 matrix.
• To elucidate the origin and mechanism of magnetic anisotropy in this multiferroic nanocomposite.
• To explore the potential applications of these vertically aligned nanopillars.

Main Methods:

• Magnetometry to identify magnetic phases and anisotropy.
• Micromagnetic simulations to model magnetization reversal.
• Polarized small-angle neutron scattering to probe nanoscale magnetization uniformity.

Main Results:

• Observation of significant out-of-plane uniaxial magnetic anisotropy in the CoFe2O4 nanopillars.
• Identification of two distinct magnetic phases with differing anisotropies.
• Micromagnetic simulations qualitatively reproduced magnetic hysteresis and revealed a core-shell magnetization reversal mechanism.

Conclusions:

• The magnetic anisotropy originates from the magnetostriction of CoFe2O4 and the stress within the nanocomposite.
• Nanoscale stress inhomogeneity influences magnetic anisotropy, providing a route to new functionalities.
• Vertically aligned nanopillars show promise for low-power memory, computing, and sensing applications.