Mott gap engineering in Sr2IrO4/SrTiO3 superlattices

• DOI: 10.1007/s40843-020-1315-8
• Publication Date: 2020-05-19T12:03:44Z
• Authors: Xin Liu; Yuben Yang; Qinghua Zhang; Dayu Yan; Jingdi Lu; Rongyan Chen; Youguo Shi; Changmin Xiong; Fa Wang; Lin Gu; Jinxing Zhang
• Keywords: band gap engineering; oxide superlattice; Sr 2 IrO 4; 0103 physical sciences; oxide superlattice Sr 2 IrO 4 band gap engineering conduction mechanism electronic structure; conduction mechanism; electronic structure; 01 natural sciences; [PHYS.COND] Physics [physics]/Condensed Matter [cond-mat]

Transition metal oxides with 5d-orbital electrons exhibit emergent quantum phenomena driven by strong spin-orbit coupling, such as Sr 2 IrO 4 with a Mott gap. Engineering of this Mott gap is highly desired for questing the novel electronic structures and functionalities in these oxides. Here, high-quality Sr 2 IrO 4 thin films and Sr 2 IrO 4 /SrTiO 3 superlattices have been grown on SrTiO 3 (001) substrates by laser molecular beam epitaxy. The electrical transport properties have been investigated, where thermal activation and the Mott variable range hopping models dominate in Sr 2 IrO 4 thin films and Sr 2 IrO 4 /SrTiO 3 superlattices respectively. A reconstruction of the band structure across the oxide interfaces plays significant role in engineering the band gap from 270.7 meV to 81.4 meV in the superlattices, which is mainly attributed to an increased bandwidth from the electronic delocalization near the Ir-O-Ti interface. Our results demonstrate that interfacial engineering in superlattices could be an effective way to atomically tailor the band structures of strongly correlated oxides.