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arXiv · 2507.09502

Electronic and magnetic ground states of {112} grain boundary in graphene in the extended Hubbard model

Sishir Jana·Dayasindhu Dey·Manoranjan Kumar·S. Ramasesha·Rajamani Raghunathan
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Abstract

We study the ground state phase diagram of the extended Hubbard model in a half-filled 5/7 skewed ladder, which is topologically equivalent to a \{112\} grain boundary in graphene and related systems. Using the mean-field method, we identify various electronic and magnetic phases in the U-V plane, by calculating the site charge and spin densities. The electronic phases include partially charge-ordered metal or insulator, and fully charge-ordered insulator. The different magnetic phases of the model are non-magnet, spin density wave, spin split compensated ferrimagnet or partial antiferromagnet. Analysis of the electronic band structure reveals that the partially charge-ordered compensated ferrimagnetic phase exhibits spin polarisation, which can be quite interesting for spintronics applications. We also compute the polarisation as a function of $U$ using the Berry phase formalism and show that the system exhibits multiferroicity with coexisting compensated ferrimagnetic spin order alongside electronic polarisations.

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Sishir Jana, Dayasindhu Dey, Manoranjan Kumar, S. Ramasesha, Rajamani Raghunathan. 2025-07-13. Electronic and magnetic ground states of {112} grain boundary in graphene in the extended Hubbard model. https://arxiv.org/abs/2507.09502

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