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Updated: Apr 11, 2026

Author Spotlight: Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks

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Coulomb parameters and ferromagnetic couplings in CoTiO₃

Yujing Wang¹, Jingtao Huang¹, Guoren Zhang¹

¹School of Physical Science and Technology, Nantong University, Nantong 226019, People's Republic of China.

Journal of Physics. Condensed Matter : an Institute of Physics Journal

|April 9, 2026

Summary

Investigating Coulomb parameters in CoTiO3 Kitaev materials, this study found d-d superexchanges insufficient for ferromagnetic couplings. Other mechanisms, like charge-transfer, are likely necessary for CoTiO3 magnetism.

Area of Science:

Condensed Matter Physics
Materials Science
Quantum Chemistry

Background:

Coulomb parameters are crucial for understanding magnetic exchange interactions.
CoTiO3 is a candidate material for Kitaev physics, exhibiting complex magnetic behavior.

Purpose of the Study:

To determine reasonable Coulomb parameters (U and J_H) for CoTiO3.
To calculate d-d superexchange couplings in CoTiO3 using first-principles methods.
To assess the contribution of d-d superexchange to the observed ferromagnetic couplings.

Main Methods:

Constrained random-phase approximation (cRPA) to determine Coulomb parameters.
Many-body perturbation theory to calculate d-d superexchange couplings.
Integration of cRPA parameters with material-specific hopping parameters.

Main Results:

The lower limit of direct Coulomb interaction (U) and upper limit of Hund's rule exchange (J_H) were specified for CoTiO3.
Calculated d-d superexchange couplings were found to be insufficient to explain the dominant ferromagnetic interactions.
This suggests that d-d superexchange alone does not govern the magnetism in CoTiO3.

Conclusions:

The magnetic properties of CoTiO3 cannot be solely explained by d-d superexchange couplings.
Charge-transfer processes and other mechanisms likely play a significant role in the ferromagnetic couplings observed in CoTiO3.
Accurate Coulomb parameters are essential for theoretical investigations of magnetic materials.

Keywords:

CoTiO3 Coulomb parameters ferromagnetic couplings

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