Extreme disorder in crystalline perovskite oxide: a new paradigm in quantum materials research

TL;DR

Compositionally complex perovskite oxides (CCPOs) introduce extreme chemical disorder into AB O3 lattices, reshaping local structure and electronic correlations to access phases inaccessible in conventional oxides. The paper surveys synthesis, local and global structural characterization, and the impact of A-, B-, and mixed-site disorder on electronic transport, dielectric, thermoelectric, orbital, and magnetic properties, highlighting how strain, defects, and local polymorphism control functionality. It reports phenomena such as disorder-tuned metal–insulator transitions, polymorphic relaxor behavior with high energy storage, strong phonon scattering leading to low lattice thermal conductivity, and emergent magnetism arising from percolated and frustrated exchange networks under high-entropy design. The authors argue for data-driven, high-throughput, and time-domain approaches to map structure–property–dynamics interrelations in CCPOs, envisioning a path toward engineered quantum materials with controllable correlated states.

Abstract

Perovskite oxides ($AB$O$_3$) have long been central to the advancement of modern condensed matter physics, owing to their rich and tunable electronic and magnetic properties. The quest to understand their various entangled phases has spurred the development of both cutting-edge experimental tools and innovative theoretical frameworks. In recent times, the emergence of high entropy oxides - materials in which five or more elements share a single crystallographic site - has introduced a powerful new paradigm in materials design. Embedding such extreme chemical disorder within the perovskite framework has opened vast opportunities for realizing novel physical phenomena inaccessible in conventional oxides. This review surveys the rapid advances in the synthesis, characterization, and exploration of the electronic and magnetic properties of compositionally complex perovskite oxides, offering key insights and highlighting promising avenues for future research.

Figures (10)

• Figure 1: Schematic illustration to highlight the tuning parameters for perovskite oxide properties such as carrier doping, strain engineering, quantum confinement, thermal excitation, etc. 'Compositional complexity' is highlighted as an additional, recently recognized control knob that encapsulates the capacities of introducing chemical inhomogeneity, lattice distortions, spin, charge, and orbital disorders at the local scale.
• Figure 2: Concept of high entropy alloy. Body-centered cubic (BCC) structure schematics for increasing number ($N$) of elements (a) $N$ = 1, (b) $N$ = 2, and (c) $N$ = 3. (d) Configurational entropy change, $S_\mathrm{conf}$ = $-R (xlnx+(1-x)ln(\frac{1-x}{N-1}))$, calculated by varying the concentration $x$ of one species while keeping the remaining $N-1$ components equimolar, shown for $N$ = 2, 3, 4, 5. (e) Maximum configurational entropy as a function of the number of elements ($N$= 2 - 10) Aamlid:2023p5991. (f) The four core effects of high-entropy design in multi-component alloys: (i) the high-entropy effect, which stabilizes single-phase solid solutions and suppresses brittle intermetallic formation Yeh:2013p1759; (ii) severe lattice distortion, which enhances hardness and strength while reducing thermal effect; (iii) sluggish diffusion, leading to slower grain growth and finer precipitates that improve strength and rigidity Liu:2013p526 and (iv) the cocktail effect, which introduces synergistic atomic-scale to microscale interactions that benefit high-temperature performance Ranganathan:2003Murty:2019y2019. Collectively, these effects substantially enhance the mechanical and thermal properties and plasticity of HEAs George:2019p515Hsu:2024p471Zhang:2013p1455Chen:2021p4953Li:2016p227.
• Figure 3: (a) Rock-salt, (b) fluorite, (c) rutile, (d) perovskite, (e) monoclinic, (f) bixbyite, (g) spinel, (h) pyrochlore, and (i) magnetoplumbite structures commonly adopted by TMOs. (j) Schematic of a half-doped perovskite manganite illustrating the coupled charge, orbital, and CE-type antiferromagnetic ordering, adapted from Ref. Ulbrich:2011p094453.
• Figure 4: Effect of compositional complexity on local structure in perovskite oxides: (a) Space groups corresponding to different octahedral rotational patterns in perovskites, along with their Glazer notations. The continuous lines denote first-order transitions, while dashed lines indicate second-order–like transitions. The absence of connecting lines between two symmetries signifies the lack of a group–subgroup relationship (Adapted from Ref. Howard:1998p782 with permission). (b) Atomic structure and compositional fluctuation revealed by annular bright-field (ABF) imaging along the [110] zone axis (upper panel), and the distribution of TM–O–TM bond angles in (5RE$_{0.2}$)(5TM$_{0.2}$)O$_3$ (lower panel) (c) Compositional fluctuation with nanoscale ordering and associated local octahedral distortions in an orthorhombic CCPO. Fig. \ref{['Fig4']}(b-c) have been adapted from Ref. Su:2022p2358 with permission.(d) Half-order diffraction around ($H'$, $K'$, $L'$) and corresponding $\delta L = L-L'$ scans for a (LaPrNdSmEu)$_{0.2}$NiO$_3$ film on NdGaO$_3$, and (e) in-plane bond-angle distribution obtained from ABF-STEM imaging of the same film. The Fig. \ref{['Fig4']}(d-e) have been adapted from Ref. Bhattacharya:2025p2418490 with permission.
• Figure 5: Electronic phase diagram for perovskite TMOs based on their correlated energy scales ($U$ and $\Delta$ scaled by the bandwidth $W$) and electronic configurations, adapted from Ref. Imada:1998p1039. The introduction of compositional complexity can be considered as the 3$^{rd}$ dimension to the phase space. Several families of CCPOs have recently been synthesized and investigated.