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Automated Materials Discovery Platform Realized: Scanning Probe Microscopy of Combinatorial Libraries
Authors:
Yu Liu,
Aditya Raghavan,
Utkarsh Pratiush,
Maxim Ziatdinov,
Chih-Yu Lee,
Rohit Pant,
Ichiro Takeuchi,
Pochun Hsieh,
Albert Suceava,
Edgar Dimitrov,
Mauricio Terrones,
Venkatraman Gopalan,
Ian Mercer,
R. Jackson Spurling,
Jon-Paul Maria,
Sergei V. Kalinin
Abstract:
Combinatorial materials libraries provide a powerful platform for mapping how physical properties evolve across binary and ternary cross-sections of multicomponent phase diagrams. While synthesis of such libraries has advanced since the 1960s and been accelerated by laboratory automation, their broader utility depends on rapid, quantitative measurements of composition-dependent structures and func…
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Combinatorial materials libraries provide a powerful platform for mapping how physical properties evolve across binary and ternary cross-sections of multicomponent phase diagrams. While synthesis of such libraries has advanced since the 1960s and been accelerated by laboratory automation, their broader utility depends on rapid, quantitative measurements of composition-dependent structures and functionalities. Scanning probe microscopies (SPM), including piezoresponse force microscopy (PFM), offer unique potential for providing these functionally relevant, spatially resolved readouts. Here, we demonstrate a fully automated SPM framework for exploring ferroelectric properties across combinatorial libraries, focusing on binary Sm-doped BiFeO3 (SmBFO) and ternary Al$_{1-x-y}$Sc$_x$B$_y$N (Al,Sc,B)N systems. In SmBFO, automated exploration identifies the known morphotropic phase boundary with enhanced ferroelectric response and reveals a previously unreported double-peak fine structure. In the (Al,Sc,B)N library, ferroelectric behavior emerges at the phase-stability boundary, correlating with variations in morphology and defect concentration. By integrating automated SPM with wavelength-dispersive spectroscopy (WDS) and photoluminescence mapping, we resolve the composition-morphology-defect-property relationships underlying ferroelectric response and demonstrate a pathway toward a multi-tool, high-throughput characterization platform. Finally, we implement Gaussian-process-based single- and multi-objective Bayesian optimization to enable autonomous exploration, highlighting the Pareto front as a powerful framework for balancing competing physical rewards and accelerating data-driven physics discovery.
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Submitted 17 November, 2025; v1 submitted 23 December, 2024;
originally announced December 2024.
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On the Structure of Vacancy Ordered Superconducting Alkali Metal Iron Selenide
Authors:
P. Zavalij,
Wei Bao,
X. F. Wang,
J. J. Ying,
X. H. Chen,
D. M. Wang,
J. B. He,
X. Q. Wang,
G. F Chen,
P-Y Hsieh,
Q. Huang,
M. A. Green
Abstract:
With single crystal X-ray diffraction studies, we compare the structures of three sample showing optimal superconductivity, K0.774(4)Fe1.613(2)Se2, K0.738(6)Fe1.631(3)Se2 and Cs0.748(2)Fe1.626(1)Se2. All have an almost identical ordered vacancy structure with a ({\sqrt}5 x {\sqrt}5 x 1) super cell. The tetragonal unit cell, space group I4/m, possesses lattice parameters at 250K of a = b = 8.729(2)…
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With single crystal X-ray diffraction studies, we compare the structures of three sample showing optimal superconductivity, K0.774(4)Fe1.613(2)Se2, K0.738(6)Fe1.631(3)Se2 and Cs0.748(2)Fe1.626(1)Se2. All have an almost identical ordered vacancy structure with a ({\sqrt}5 x {\sqrt}5 x 1) super cell. The tetragonal unit cell, space group I4/m, possesses lattice parameters at 250K of a = b = 8.729(2) Å and c = 14.120(3) Å, a = b = 8.7186(12) Å and c = 14.0853(19) Å and at 295 K, a = b = 8.8617(16) Å and c = 15.304(3) Å for the three crystals, respectively. The structure contains two iron sites; one is almost completely empty, whilst the other is fully occupied. There are similarly two alkali metal sites that are occupied in the range of 72.2(2) % to 85.3(3) %. The inclusion of alkali metals and the presence of vacancies within the structure allows for considerable relaxation of the FeSe4 tetrahedron, compared with members of the Fe(Te, Se, S) series, and the resulting shift of the Se - F - Se bond angles to less distorted geometry could be important in understanding the associated increase in the superconducting transition temperature. The structure of these superconductors distinguishes themselves from the structure of the non-superconducting phases by an almost complete absence of Fe on the (0 0.5 0.25) site as well as lower alkali metal occupancy that ensures an exact Fe2+ oxidation state, which are clearly critical parameters in the promotion of superconductivity.
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Submitted 11 February, 2011; v1 submitted 25 January, 2011;
originally announced January 2011.
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Interstitial Iron Controlled Superconductivity in Fe1+xTe0.7Se0.3
Authors:
E. E. Rodriguez,
C. Stock,
P-Y Hsieh,
N. Butch,
J. Paglione,
M. A. Green
Abstract:
The superconducting series, Fe(Te,Se), has a complex structural and magnetic phase diagram that is dependent on composition and occupancy of a secondary interstitial Fe site. In this letter, we show that superconductivity in Fe1+xTe0.7Se0.3 can be enhanced by topotactic deintercalation of the interstitial iron, demonstrating the competing roles of the two iron sites. Neutron diffraction reveals a…
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The superconducting series, Fe(Te,Se), has a complex structural and magnetic phase diagram that is dependent on composition and occupancy of a secondary interstitial Fe site. In this letter, we show that superconductivity in Fe1+xTe0.7Se0.3 can be enhanced by topotactic deintercalation of the interstitial iron, demonstrating the competing roles of the two iron sites. Neutron diffraction reveals a flattening of the Fe(Te,Se)4 tetrahedron on Fe removal of iron and an increase in negative thermal expansion within the ab plane that correlates with increased lattice strain. Inelastic neutron scattering shows that a gapped excitation at 6 meV, evolves into gapless paramagnetic scattering with increasing iron; similar to the fluctuations observed for non-superconducting Fe1+xTe itself.
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Submitted 2 December, 2010;
originally announced December 2010.