Regensburg 2022 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 38: Electron Theory of Magnetism and Correlations

MA 38.3: Vortrag

Freitag, 9. September 2022, 10:00–10:15, H43

Double-Exchange Enhanced Magnetic Blue-Shift of Mott Gaps — •Mohsen Hafez-Torbati¹, Davide Bossini², Frithjof B. Anders¹, and Goetz S. Uhrig¹ — ¹Technical University of Dortmund, Dortmund, Germany — ²University of Konstanz, Konstanz, Germany

Strong correlations in Mott insulators induce a substantial charge excitation energy known as the Mott gap. We study how the Mott gap is affected by long-range antiferromagnetic ordering upon reducing the temperature below the Néel temperature. Our finding is that the Mott gap is increased by the magnetic ordering: a magnetic blue-shift (MBS) occurs. We unveil the origin of the MBS of the Mott gap by analyzing the Hubbard model and the Hubbard-Kondo model and clarify the subtle differences. We show that in the Hubbard model the MBS is determined by the magnetic exchange coupling. In the Hubbard-Kondo model an additional contribution proportional to the hopping is induced by the double-exchange mechanism. We describe the magnetic contribution to the band gap blue-shift observed in the optical conductivity of α-MnTe and pinpoint a hopping contribution of 64% and a magnetic exchange contribution of 36%. A MBS with the energy scale of the hopping and the exchange interaction bears the potential to enable spin-to-charge conversion on extreme time scales, highly promising for spintronic and magnonic applications.