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Anomalous Magnetodielectric Effect in the Metal-Organic Framework [CH3NH3][Co(HCOO)3]
Shuang Liu1, Na Su1, Kaiqi Zhang1
1Department of Applied Physics and Center of Quantum Materials and Devices, Chongqing University, Chongqing 401331, China.
Inorganic Chemistry
|March 3, 2025
Summary
We discovered an anisotropic magnetodielectric effect in [CH3NH3][Co(HCOO)3] metal-organic frameworks. Strong magnetic anisotropy drives significant dielectric changes, offering insights into spin-lattice coupling mechanisms.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Magnetism
Background:
- Metal-organic frameworks (MOFs) are versatile materials with tunable properties.
- Magnetodielectric effects, where magnetic fields influence dielectric properties, are of significant scientific interest.
- Understanding anisotropic effects in magnetic materials is crucial for developing advanced electronic devices.
Purpose of the Study:
- To investigate the anisotropic magnetodielectric effect in single crystals of perovskite methylammonium cobalt formate ([CH3NH3][Co(HCOO)3]).
- To elucidate the relationship between magnetic anisotropy, spin reorientation, and dielectric responses in this MOF.
- To explore the underlying mechanisms, including spin fluctuations and spin-lattice coupling, governing the magnetodielectric phenomenon.
Main Methods:
- Single-crystal growth of [CH3NH3][Co(HCOO)3].
- Anisotropic magnetodielectric measurements at low temperatures (2 K) and varying magnetic fields (up to 9 T).
- Analysis of dielectric response in relation to magnetic ordering and spin reorientation phenomena.
Main Results:
- A notable dielectric peak was observed at 2 K during spin reorientation along the [101] direction.
- A pronounced positive magnetodielectric effect was found along the [010] direction due to ferromagnetic ordering and strong magnetic anisotropy.
- Maximum magnetodielectric effects (Δε/ε of -0.31% along [101] and -0.23% along [010]) occurred at the magnetic ordering temperature under a 9 T field.
- A weak magnetodielectric effect persisted up to 150 K in the paramagnetic state, potentially due to magnetostriction.
Conclusions:
- The study highlights the significant role of magnetic anisotropy in driving the magnetodielectric effect in [CH3NH3][Co(HCOO)3] MOFs.
- Strong spin fluctuations at the magnetic ordering temperature enhance the magnetodielectric response.
- The findings provide valuable insights into spin-lattice coupling and magnetostrictive effects in metal-organic frameworks, relevant for future materials design.
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