Isostructural metal-insulator transition driven by dimensional-crossover in ${\mathrm{SrIrO}}_{3}$ heterostructures

Isostructural metal-insulator transition driven by dimensional-crossover in ${SrIrO}_{3}$ heterostructures

Shuai Kong, Lei Li, Zengxing Lu, Jiatai Feng, Xuan Zheng, Pengbo Song, You-guo Shi, Yumei Wang, Binghui Ge, Katharina Rolfs, Ekaterina Pomjakushina, Thorsten Schmitt, Nicholas C. Plumb, Ming Shi, Zhicheng Zhong, Milan Radovic, Zhiming Wang, and Run-Wei Li

Phys. Rev. Materials 6, 034404 – Published 21 March 2022

Abstract

Dimensionality reduction induced metal-insulator transitions in oxide heterostructures are usually coupled with structural and magnetic phase transitions, which complicate the interpretation of the underlying physics. Therefore, achieving isostructural MIT is of great importance for fundamental physics and even more for applications. Here, we report an isostructural metal-insulator transition driven by dimensional-crossover in spin-orbital coupled ${SrIrO}_{3}$ films. By using in situ pulsed laser deposition and angle-resolved photoemission spectroscopy, we synthesized and investigated the electronic structure of ${SrIrO}_{3}$ ultrathin films with atomic-layer precision. Through inserting orthorhombic ${CaTiO}_{3}$ buffer layers, combined low-energy electron diffraction measurements and first-principles density functional theory calculations show that the crystal structure of ${SrIrO}_{3}$ films remains bulklike with similar oxygen octahedra rotation and tilting when approaching the ultrathin limit. We observe that a dimensional-crossover metal-insulator transition occurs in isostructural ${SrIrO}_{3}$ films. Intriguingly, we find the bandwidth of $J_{eff} = 3 / 2$ states reduces with lowering the dimensionality and drives the metal-insulator transition. Our results establish a bandwidth controlled metal-insulator transition in the isostructural ${SrIrO}_{3}$ thin films.

Received 17 November 2020
Revised 26 January 2022
Accepted 7 March 2022

DOI:https://doi.org/10.1103/PhysRevMaterials.6.034404

Physics Subject Headings (PhySH)

Electronic structure Surface & interfacial phenomena

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Shuai Kong^1,2,3,*, Lei Li^1,2,3,*, Zengxing Lu^1,2,3,*, Jiatai Feng ^1,2,3, Xuan Zheng^1,3,4, Pengbo Song⁵, You-guo Shi⁵, Yumei Wang⁵, Binghui Ge⁶, Katharina Rolfs⁷, Ekaterina Pomjakushina⁷, Thorsten Schmitt⁸, Nicholas C. Plumb⁸, Ming Shi⁸, Zhicheng Zhong^1,2,3,†, Milan Radovic^8,9,‡, Zhiming Wang ^1,2,3,§, and Run-Wei Li^1,2,3

¹Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
²Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
³Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
⁴Department of Chemical and Environmental Engineering, The University of Nottingham, Ningbo 315100, China
⁵Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
⁶Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China
⁷Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
⁸Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
⁹SwissFEL, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland

^*These authors contributed equally to this work.
^†zhong@nimte.ac.cn
^‡milan.radovic@psi.ch
^§zhiming.wang@nimte.ac.cn

Article Text (Subscription Required)

Click to Expand

Supplemental Material (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand

Issue

Vol. 6, Iss. 3 — March 2022

Reuse & Permissions

Access Options

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
Control of oxygen octahedral out-of-plane tilting in ${SrIrO}_{3} / {CaTiO}_{3}$ heterostructures. (a) DFT calculated structure of the ${SrIrO}_{3} / {CaTiO}_{3}$ heterostructure on Nb: ${SrTiO}_{3}$ substrate. (b) DFT calculated layer-dependent tilting angle of the heterostructure. (c) The octahedral out-of-plane tilting and (d) in-plane rotation angles as a function of film thickness with and without ${CaTiO}_{3}$ buffer layers. The octahedral tilting is roughly independent on the film thickness after interfacing buffer layers. (d) Top view of structural model. The octahedral out-of-plane tilting and in-plane rotation produce a 2 × 2 surface periodicity, which has been observed by LEED pattern in 10-, 5-, 2-u.c. ${SrIrO}_{3}$ with ${CaTiO}_{3}$ buffer layers (f)–(h).
Reuse & Permissions
Figure 2
Dimensional-crossover driven metal-insulator transition in isostructural ${SrIrO}_{3}$ . (a) The three dimensional Brillouin zone (BZ) of orthorhombic ${SrIrO}_{3}$ . (b) Fermi surface intensity map measured on 10-u.c. ${SrIrO}_{3} / {CaTiO}_{3}$ heterostructure. (c) Energy vs momentum intensity maps along Γ- $X$ direction with decreasing ${SrIrO}_{3}$ thickness. (d) Energy distribution curves (EDCs) at the Fermi wave vector indicated by the vertical line in the corresponding image plots in (c). An exponential background has been subtracted from the raw EDCs (see Supplemental Material Fig. S2 [36]). (e) The comparison of quasiparticle residue $Z$ and tilting angles for ${SrIrO}_{3}$ films grown with and without ${CaTiO}_{3}$ buffer layers. All data were taken at a photon energy of 82 eV with circular polarization and at temperature of 14 K.
Reuse & Permissions
Figure 3
Thickness-dependent evolution of chemical shift. The spectra of (a) Ir $4 f$ core level and (b) O $2 p$ valence band as a function of film thickness. The peak positions are marked with black lines. (c) The relative peak shift of both O $2 p$ and Ir $4 f$ with reference to that of the thick ${SrIrO}_{3}$ film.
Reuse & Permissions
Figure 4
Mechanism of dimensional-crossover driven metal-insulator transition in isostructural ${SrIrO}_{3}$ . The photoemission intensity plots of (a) 10-u.c. and (b) 3-u.c. ${SrIrO}_{3}$ with ${CaTiO}_{3}$ buffer layers taken along Γ- $X$ high symmetry direction. (a),(d) The corresponding second-derivative plots. (e) Evolution of the $J_{eff} = 3 / 2$ states around Γ point. The data are extracted from (a)–(d) as a function of film thickness. Details are described in Supplemental Material Fig. S5 [36]. (f) Evolution of band top and bottom position of the $J_{eff} = 3 / 2$ states. (g) The thickness-dependent evolution in bandwidth of $J_{eff} = 3 / 2$ and $J_{eff} = 1 / 2$ states.
Reuse & Permissions

Physical Review Materials

Isostructural metal-insulator transition driven by dimensional-crossover in SrIrO3 heterostructures

Shuai Kong, Lei Li, Zengxing Lu, Jiatai Feng, Xuan Zheng, Pengbo Song, You-guo Shi, Yumei Wang, Binghui Ge, Katharina Rolfs, Ekaterina Pomjakushina, Thorsten Schmitt, Nicholas C. Plumb, Ming Shi, Zhicheng Zhong, Milan Radovic, Zhiming Wang, and Run-Wei Li

Phys. Rev. Materials 6, 034404 – Published 21 March 2022

Abstract

Physics Subject Headings (PhySH)

Authors & Affiliations

Article Text (Subscription Required)

Supplemental Material (Subscription Required)

References (Subscription Required)

Issue

Access Options

Authorization Required

Other Options

Download & Share

Images

Figure 1

Figure 2

Figure 3

Figure 4

Log In

Search

Article Lookup

Paste a citation or DOI

Enter a citation

Isostructural metal-insulator transition driven by dimensional-crossover in ${SrIrO}_{3}$ heterostructures