Correlation driven metallic and half-metallic phases in a band insulator

We demonstrate a mechanism for realizing ferrimagnetic metal, antiferromagnetic half-metal, and paramagnetic metal phases by tuning the onsite Coulomb repulsion U in a band insulator. In a simple model of a correlated band insulator, namely the ionic Hubbard model at half-filling, and in the presenc...

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Bibliographic Details
Published in:Physical review. B 2021-04, Vol.103 (15), p.1, Article 155132
Main Authors: Bag, Soumen, Garg, Arti, Krishnamurthy, H. R.
Format: Article
Language:English
Subjects:
Antiferromagnetism
Mean field theory
Phases
Spintronics
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Summary:We demonstrate a mechanism for realizing ferrimagnetic metal, antiferromagnetic half-metal, and paramagnetic metal phases by tuning the onsite Coulomb repulsion U in a band insulator. In a simple model of a correlated band insulator, namely the ionic Hubbard model at half-filling, and in the presence of a second neighbor hopping, we show that as U is increased, first he insulating band gap is suppressed to zero at a critical U 1 and remains zero within the paramagnetic metallic phase. Interestingly, at a larger Uc, ferrimagnetic order turns on, leading to a ferrimagnetic metallic phase for Uc < U < U2. For U > U2, the system exhibits an antiferromagnetic half-metallic phase, followed finally by a transition into an antiferromagnetic Mott insulator. Our results, based on dynamical mean-field theory, suggest alternate routes for achieving magnetically ordered metallic and half-metallic phases which have potential applications in spintronics.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.103.155132