Double-Exchange Enhanced Magnetic Blue-Shift of Mott Gaps

Abstract

A substantial energy gap of charge excitations induced by strong correlations is the characteristic feature of Mott insulators. We study how the Mott gap is affected by long-range antiferromagnetic order. Our key finding is that the Mott gap is increased by the magnetic ordering: a magnetic blue-shift (MBS) occurs. Thus, the effect is proportional to the exchange coupling in the leading order in the Hubbard model. In systems with additional localized spins the double-exchange mechanism induces an additional contribution to the MBS which is proportional to the hopping in the leading order. The coupling between spin and charge degrees of freedom bears the potential to enable spin-to-charge conversion in Mott systems on extreme time scales determined by hopping and exchange only, since a spin-orbit mediated transfer of angular momentum is not involved in the process. In view of spintronic and magnonic applications, it is highly promising to observe that several entire classes of compounds show exchange and double-exchange effects. Exemplarily, we show that the magnetic contribution to the band-gap blue-shift observed in the optical conductivity of $\alpha$-MnTe is correctly interpreted as the MBS of a Mott gap.

13 pages, 12 figures

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Cited by in corpus (7)

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• Tuning the magnetic properties of the spin-split antiferromagnet MnTe through pressure
• Simplified approach to the magnetic blue shift of Mott gaps
• Antiferromagnetic Chern insulator with large charge gap in heavy transition-metal compounds
• Asymmetry effects on the phases of RKKY-coupled two-impurity Kondo systems
• Antiferromagnetic topological insulators in heavy-fermion systems
• High-Temperature Quantum Anomalous Hall Effect in Buckled Honeycomb Antiferromagnets