Scientific Challenge

The energy transition depends on placing materials at narrow operating points in high-dimensional compositional space: catalysts that split water without platinum, magnetocalorics that refrigerate without hydrofluorocarbons, electrodes that store charge reversibly. The scientific question is physical: which features of the electronic structure actually decide whether a material sits at that operating point, and which are incidental? The functional target is macroscopic, but the control variable—Fermi-level position relative to a pseudogap, d-band filling, site-resolved d-band centre—is electronic and atomic. Compositional design becomes predictive only when those control variables are isolated cleanly enough to be tuned deliberately.

Our Approach

We identify problems where a clean electronic-structure control parameter exists, so that trends across composition or site substitution can be read as causal mechanisms rather than statistical patterns. Studies are designed factorially—hole-doping against electron-doping at the same site, isovalent metal pairs across groups, anion substitution at fixed valence electron count—so that the variable doing the work is isolated by construction.

Disorder is treated as the object of study rather than a numerical inconvenience. Methods are chosen to match the physics: Green’s-function coherent potential approximation for substitutional alloys, explicit supercells where short-range order matters, high-throughput screening along controlled compositional axes, Lichtenstein-formalism exchange extraction where the question is about exchange topology.

We take seriously the step from local descriptor to collective response. A favourable d-band centre is not a catalyst, and a large local moment is not a magnet. When we report a Curie temperature, we also report the exchange competition parameter that says how much of it survives the cancellation between ferromagnetic and antiferromagnetic pathways.

Key Insights & Achievements

• Fermi-level engineering of itinerant magnetism. In B2-ordered FeRh under substitutional disorder, hole- and electron-doping on the magnetic sublattice resolve the chemical-versus-magneto-volume question: Fermi-level position relative to the minority-spin pseudogap, not the lattice parameter, decides whether the Curie temperature collapses or holds—establishing d-band filling as a predictive control variable for itinerant ferromagnets.
• Site-resolved descriptors for catalysis. In bimetallic Janus MXenes, factorial screening across metal pairs and anions shows that site-resolved d-band asymmetry—not a sublattice-averaged descriptor—controls hydrogen adsorption near thermoneutrality, and identifies the regime (magnetic exchange splitting on one sublattice) where the local descriptor breaks down.
• Doping pathways to noble-metal-free catalysis. In layered transition-metal carbides and nitrides, targeted electronic-structure engineering through early-transition-metal doping brings hydrogen adsorption into the thermoneutral window without requiring platinum-group metals.
• Exchange topology as a design handle. Across all-d-metal and Zn-based Heusler magnetocalorics, mapping the competition between ferromagnetic and antiferromagnetic exchange pathways identifies compositional routes to room-temperature operation and unconventional critical behaviour.

These results establish that macroscopic function in energy-relevant itinerant systems can be traced to a small number of electronic-structure control parameters, and that identifying those parameters cleanly is what makes compositional design predictive. These insights guide experimental design of magnetocalorics, catalysts, and spintronic materials.

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