Metal–insulator-transition engineering by modulation tilt-control in perovskite nickelates for room temperature optical switching

Abstract

SignificanceCorrelated transition metal oxide perovskites receive a lot of attention due to their unique physical properties, which are largely driven by distortion of the BO6 octahedral network. In bulk, the control of the octahedral network is normally obtained by cation substitutions in a random alloy. Similar to the charge donors in semiconductors, cation substitutions will introduce scattering and disorder. The development of artificial heterostructures offers unprecedented opportunities to lattice engineering to achieve desired properties. In this work, we demonstrated a structural analogue of modulation doping in nickelate heterostructures through the interfacial transfer of tilt patterns. Modulation tilt control was used to remotely control the Ni–O bonds in the compound SmNiO3 and thereby its critical temperature for optimal optical switching application.

Atomic‐Scale Control of Electronic Structure and Ferromagnetic Insulating State in Perovskite Oxide Superlattices by Long‐Range Tuning of BO6 Octahedra

“…In summary, we have employed the LBMO/STO superlattices as a model system to demonstrate an extensive control of MnO 6 octahedral rotations with greatly enhanced OOC impact length of up to 12 uc, compared to the previously reported 2-6 uc. [15][16][17][21][22][23][24] Suppression of MnO 6 octahedral rotations leads to a change of magnetic exchange interactions, a reduced Mn e g bandwidth and orbital reconstruction. Consequently, an emergent ferromagnetic insulating state is realized in LBMO with an enhanced T C of 235 K, which is significantly higher than that of bulk LBMO (185 K).…”

“…[15][16][17] However, as shown in the left sketch in Figure 1a, the major drawback of OOC is that its impact length scale is only 2-6 unit cells (uc) confined at the interface region, and the modulation of BO 6 octahedral rotations decays very quickly away from interface. [15][16][17][21][22][23][24] Therefore, an enhancement of the impact length is highly desirable in order to extend the tuning of emergent effects beyond the interfacial region and to achieve a large volume of material, comprising novel functionalities for both fundamental studies and device applications.…”

“…In this study, by carefully growing a series of (LBMO)N-(STO)N (noted as LNSN; N = 4, 5, 6, 8, 9, 10, 12, and 14) superlattices, we demonstrate that the modulation of MnO 6 octahedral rotations in LBMO could be extended up to 12 uc which is significantly increased in comparison to previously reported OOC length scale of 2-6 uc. [15][16][17][21][22][23][24] O K-edge X-ray absorption spectroscopy (XAS), X-ray magnetic circular dichroism (XMCD) and linear dichroism (XLD) and density functional theory (DFT) calculations reveal that when interfacial MnO 6 octahedral rotations are strongly suppressed, the Mn e g bandwidth is reduced and orbital reconstructions occur in the Mn 3d orbitals. This in turn modifies the magnetic and electronic ground states of the manganite and creates an emergent ferromagnetic insulating state in LBMO with an increased T C of 235 K.…”

Mechanism and control parameters of the coupled structural and metal-insulator transition in nickelates

“…Our theory also identifies the BM stiffness and the electronic susceptibility at q = ( 1 2 , 1 2 , 1 2 ) as key parameters controlling the transition. Experimentally, these parameters can be tuned by the choice of the R cation [6], or by epitaxial strain in thin films and heterostructures [9,10,34,35]. We validate our theory by performing combined DFT and dynamical mean-field theory (DMFT) [36,37] calculations, allowing us to explore the trends across the rare-earth series.…”

Probing photoinduced rearrangements in the NdNiO3 magnetic spiral with polarization-sensitive ultrafast resonant soft x-ray scattering

“…Rare-earth nickelates exhibit sharp metal-insulator transitions and unusual noncollinear antiferromagnetic (AFM) spin ordering at low temperatures [1], which may become interesting for device applications [2]. Amongst these nickelate compounds, we analyze NdNiO 3 -a material that exhibits exceptionally strong coupling of structural, electronic, and spin degrees of freedom.…”