Microscopic and Spectroscopic Evidence for a Slater Metal-Insulator Transition in Sr2IrO4
Abstract
Layered 5d transition metal oxides (TMOs) have attracted significant interest in recent years because of the rich physical properties induced by the interplay between spin-orbit coupling, bandwidth and on-site Coulomb repulsion. In Sr2IrO4, this interplay opens a gap near the Fermi energy and stabilizes a Jeff=1/2 spin-orbital entangled insulating state at low temperatures. Whether this metal-insulating transition (MIT) is Mott-type (electronic-correlation driven) or Slater-type (magnetic-order driven) has been under intense debate. We address this issue via spatially resolved imaging and spectroscopic studies of the Sr2IrO4 surface using scanning tunneling microscopy/spectroscopy (STM/S). The STS results clearly illustrate the opening of the (~150-250 meV) insulating gap at low temperatures, in qualitative agreement with our density-functional theory (DFT) calculations. More importantly, the measured temperature dependence of the gap width coupled with our DFT+dynamical mean field theory (DMFT) results strongly support the Slater-type MIT scenario in Sr2IrO4. The STS data further reveal a pseudogap structure above the Neel temperature, presumably related to the presence of antiferromagnetic fluctuations.
Keywords
Cite
@article{arxiv.1303.7265,
title = {Microscopic and Spectroscopic Evidence for a Slater Metal-Insulator Transition in Sr2IrO4},
author = {Qing Li and Guixin Cao and Satoshi Okamoto and Jieyu Yi and Wenzhi Lin and Brian C. Sales and Jiaqiang Yan and Ryotaro Arita and Jan Kunes and Anton V. Kozhevnikov and Adolfo G. Eguiluz and Masatoshi Imada and Zheng Gai and Minghu Pan and David G. Mandrus},
journal= {arXiv preprint arXiv:1303.7265},
year = {2013}
}