Observation of a Slater-type metal-to-insulator transition in Sr₂IrO₄ from time-resolved photo-carrier dynamics

2012/03/20 by Hsieh, D., Mahmood, F., Torchinsky, D. H. +2
#FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Strongly Correlated Electrons (cond-mat.str-el)

paper · doi:10.48550/arxiv.1203.4536

Abstract

We perform a time-resolved optical study of Sr₂IrO₄ to understand the influence of magnetic ordering on the low energy electronic structure of a strongly spin-orbit coupled J_eff=1/2 Mott insulator. By studying the recovery dynamics of photo-carriers excited across the Mott gap, we find that upon cooling through the Néel temperature T_N the system evolves continuously from a metal-like phase with fast (∼50 fs) and excitation density independent relaxation dynamics to a gapped phase characterized by slower (∼500 fs) excitation density dependent bimolecular recombination dynamics. The development of the insulating gap is accompanied by a transfer of in-gap spectral weight to energies far in excess of the gap and occurs over an unusually broad temperature window, which suggests Sr₂IrO₄ to be a Slater- rather than Mott-Hubbard type insulator and naturally explains the absence of anomalies at T_N in transport and thermodynamic measurements.

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