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Electronic structure of a graphene-like artificial crystal of NdNiO3

DOI: 10.1021/acs.nanolett.9b03962 DOI Help

Authors: Arian Arab (Temple University) , Xiaoran Liu (Rutgers University) , Okan Koksal (University of Duisburg-Essen) , Weibing Yang (Temple University) , Ravini U. Chandrasena (Temple University) , Srimanta Middey (Indian Institute of Science) , Mikhail Kareev (Rutgers University) , Siddharth Kumar (Indian Institute of Science) , Marius-adrian Husanu (Swiss Light Source; National Institute of Materials Physics) , Zhenzhong Yang (Beijing National Laboratory for Condensed-Matter Physics and Institute of Physics, Chinese Academy of Sciences) , Lin Gu (Beijing National Laboratory for Condensed-Matter Physics and Institute of Physics, Chinese Academy of Sciences; Collaborative Innovation Center of Quantum Matter) , Vladimir N. Strocov (Swiss Light Source) , Tien-lin Lee (Diamond Light Source) , Jan Minar (University of West Bohemia) , Rossitza Pentcheva (University of Duisburg-Essen) , Jak Chakhalian (Rutgers University) , Alexander X. Gray (Temple University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nano Letters

State: Published (Approved)
Published: October 2019

Abstract: Artificial complex-oxide heterostructures containing ultrathin buried layers grown along the pseudocubic [111] direction have been predicted to host a plethora of exotic quantum states arising from the graphene-like lattice geometry and the interplay between strong electronic correlations and band topology. To date, however, electronic-structural investigations of such atomic layers remain an immense challenge due to the shortcomings of conventional surface-sensitive probes, with typical information depths of a few Ã…ngstroms. Here, we use a combination of bulk-sensitive soft x-ray angle-resolved photoelectron spectroscopy (SX-ARPES), hard x-ray photoelectron spectroscopy (HAXPES) and state-of-the-art first-principles calculations to demonstrate a direct and robust method for extracting momentum-resolved and angle-integrated valence-band electronic structure of an ultrathin buckled graphene-like layer of NdNiO3 confined between two 4-unit cell-thick layers of insulating LaAlO3. The momentum-resolved dispersion of the buried Ni d states near the Fermi level obtained via SX-ARPES is in excellent agreement with the first-principles calculations and establishes the realization of an antiferro-orbital order in this artificial lattice. The HAXPES measurements reveal the presence of a valence-band (VB) bandgap of 265 meV. Our findings open a promising avenue for designing and investigating quantum states of matter with exotic order and topology in a few buried layers.

Journal Keywords: Strongly-correlated oxides; soft x-ray angle-resolved photoelectron spectroscopy; hard x-ray photoelectron spectroscopy

Subject Areas: Physics, Chemistry

Facility: ADRESS beamline of the Swiss Light Source