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The high-entropy strategy has gained increasing popularity in the design of functional materials due to its four core effects. In this study, we introduce the concept of a “high-entropy magnet (HEM)”, which integrates diverse magnetic compounds within a single phase and is anticipated to demonstrate unique magnetism-related properties beyond that of its individual components. This concept is exemplified in AB2-type layered Kagome intermetallic compounds (Ti,Zr,Hf,Nb,Fe)Fe2. It is revealed that the competition among individual magnetic states and the presence of magnetic Fe in originally nonmagnetic high-entropy sites lead to intricate magnetic transitions with temperature. Consequently, unusual transformations in thermal expansion property (from positive to zero, negative, and back to near zero) are observed. Specifically, a near-zero thermal expansion is achieved over a wide temperature range (10–360 K, αv= −0.62 × 10–6K–1) in the A-site equal-atomic ratio (Ti1/5Zr1/5Hf1/5Nb1/5Fe1/5)Fe2compound, which is associated with successive deflection of average Fe moments. The HEM strategy holds promise for discovering new functionalities in solid materials.

Exchange bias (EB) is a crucial property with widespread applications but particularly occurs by complex interfacial magnetic interactions after field cooling. To date, intrinsic zero-field-cooled EB (ZEB) has only emerged in a few bulk frustrated systems and their magnitudes remain small yet. Here, enabled by high temperature synthesis, we uncover a colossal ZEB field of 4.95 kOe via tuning compensated ferrimagnetism in a family of kagome metals, which is almost twice the magnitude of known materials. Atomic-scale structure, spin dynamics, and magnetic theory revealed that these compensated ferrimagnets originate from significant antiferromagnetic exchange interactions embedded in the holmium–iron ferrimagnetic matrix due to supersaturated preferential manganese doping. A random antiferromagnetic order of manganese sublattice sandwiched between ferromagnetic iron kagome bilayers accounts for such unconventional pinning. The outcome of the present study outlines disorder-induced giant bulk ZEB and coercivity in layered frustrated systems.

Accurately decoding the three-dimensional atomic structure of surface active sites is essential yet challenging for a rational catalyst design. Here, we used comprehensive techniques combining the pair distribution function and reverse Monte Carlo simulation to reveal the surficial distribution of Pd active sites and adjacent coordination environment in palladium–copper nanoalloys. After the fine-tuning of the atomic arrangement, excellent catalytic performance with 98% ethylene selectivity at complete acetylene conversion was obtained in the Pd34Cu66nanocatalysts, outperforming most of the reported advanced catalysts. The quantitative deciphering shows a large number of active sites with a Pd–Pd coordination number of 3 distributed on the surface of Pd34Cu66nanoalloys, which play a decisive role in highly efficient semihydrogenation. This finding not only opens the way for guiding the precise design of bimetal nanocatalysts from atomic-level insight but also provides a method to resolve the spatial structure of active sites.