Title: Electronic Structure of a Graphene-like Artificial Crystal of NdNiO₃

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 Ångstroms. 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. Lastly, our findings open a promising avenue for designing and investigating quantum states of matter with exotic order and topology in a few buried layers.

Authors:

Arab, Arian ^[1]; Liu, Xiaoran ^[2]; Köksal, Okan ^[3]; Yang, Weibing ^[1]; Chandrasena, Ravini U.  ^[1];

• Search DOE PAGES for author "Chandrasena, Ravini U."
• Search DOE PAGES for ORCID "0000-0001-8766-0965"

Middey, Srimanta  ^[4];

• Search DOE PAGES for author "Middey, Srimanta"
• Search DOE PAGES for ORCID "0000-0001-5893-0946"

Kareev, Mikhail ^[2]; Kumar, Siddharth ^[4]; Husanu, Marius-Adrian ^[5]; Yang, Zhenzhong ^[6]; Gu, Lin ^[7]; Strocov, Vladimir N. ^[8]; Lee, Tien-Lin ^[9]; Minár, Jan ^[10]; Pentcheva, Rossitza  ^[3];

• Search DOE PAGES for author "Pentcheva, Rossitza"
• Search DOE PAGES for ORCID "0000-0002-4423-8980"

Chakhalian, Jak ^[2]; Gray, Alexander X. ^[1]

---

+ Show Author Affiliations

1. Temple Univ., Philadelphia, PA (United States)
2. Rutgers Univ., Piscataway, NJ (United States)
3. Univ. of Duisburg-Essen, Duisburg (Germany). Center for Nanointegration Duisburg-Essen (CENIDE)
4. Indian Inst. of Science, Bengaluru (India)
5. Paul Scherrer Inst. (PSI), Villigen (Switzerland). Swiss Light Source; National Inst. of Materials Physics, Magurele (Romania)
6. Chinese Academy of Sciences (CAS), Beijing (China). Beijing National Lab. for Condensed-Matter Physics and Institute of Physics
7. Chinese Academy of Sciences (CAS), Beijing (China). Beijing National Lab. for Condensed-Matter Physics and Institute of Physics; Collaborative Innovation Center of Quantum Matter, Beijing (China)
8. Paul Scherrer Inst. (PSI), Villigen (Switzerland). Swiss Light Source
9. Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Diamond Light Source, Ltd.
10. Univ. of West Bohemia, Pilsen (Czech Republic). New Technologies-Research Center

Publication Date:

Wed Oct 23 00:00:00 EDT 2019

Research Org.:

Temple Univ., Philadelphia, PA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1774776

Grant/Contract Number:  

SC0019297

Resource Type:

Accepted Manuscript

Journal Name:

Nano Letters

Additional Journal Information:

Journal Volume: 19; Journal Issue: 11; Journal ID: ISSN 1530-6984

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Strongly correlated oxides; soft X-ray angle-resolved photoelectron spectroscopy; hard X-ray photoelectron spectroscopy; Band structure; Photoemission; Layers; Lattices; Colloids