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Updated: May 31, 2026
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Optimizing Magnetic Force Microscopy Resolution and Sensitivity to Visualize Nanoscale Magnetic Domains
Published on: July 20, 2022
Overcoming Size-Dependent Magnetic Thermal Stability via Atomical Coherence
Ao Chen1, Yuting Tang1, Zhengdong Cheng2
1Institute of Process Equipment, College of Energy Engineering, Zhejiang University, Hangzhou 310027, China.
Journal of the American Chemical Society
|May 29, 2026
Summary
Stabilizing nanoscale magnets requires overcoming thermal energy. Researchers enhanced magnetic anisotropy in FePt@MnO nanoparticles, significantly increasing their blocking temperature for stable magnetic order.
Area of Science:
- Materials Science
- Nanotechnology
- Condensed Matter Physics
Background:
- Ferromagnetic order in nanoscale magnets requires breaking time-reversal symmetry, where magnetic anisotropy energy (KeffV) must exceed thermal fluctuation energy (kBT).
- Miniaturization faces the superparamagnetic limit (KeffV = kBT at blocking temperature, TB).
Purpose of the Study:
- To concurrently enhance both magnetocrystalline and surface anisotropies in core-shell FePt@MnO nanoparticles.
- To overcome the superparamagnetic limit for improved magnetic stability in nanoscale magnets.
Main Methods:
- Fabrication of core-shell FePt@MnO nanoparticles with an atomically coherent interface, accommodating a 14% lattice mismatch.
- Characterization of magnetic properties, including effective magnetic anisotropy (Keff) and blocking temperature (TB).
- Investigation of the anomalous vertical exchange-bias effect to confirm anisotropy enhancement.
Main Results:
- Achieved concurrent enhancement of magnetocrystalline and surface anisotropies via an atomically coherent FePt-MnO interface.
- Boosted effective magnetic anisotropy (Keff ≈ 8.0 × 10^6 J/m^3) in 2 nm FePt cores, approaching bulk values.
- Increased the blocking temperature (TB) to 130 K, a 13-fold increase over bare FePt, extending magnetic stability to room temperature.
Conclusions:
- Atomically coherent interfaces in FePt@MnO nanoparticles effectively enhance magnetic anisotropy and stability.
- The achieved blocking temperature surpasses MnO's Néel temperature, enabling room-temperature operation.
- This approach broadens the applicability of nanoscale magnets in ultrahigh-density recording and medical technologies.
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