Interplanar Ferromagnetism Enhanced Ultrawide Zero Thermal Expansion in Kagome Cubic Intermetallic (Zr,Nb)Fe₂

A cubic metal exhibiting zero thermalexpansion (ZTE)over a widetemperature window demonstrates significant applications in a broadrange of advanced technologies but is extremely rare in nature. Here,enabled by high-temperature synthesis, we realize tunable thermalexpansion via magnetic doping in the class of kagome cubic (Fd-3m) intermetallic (Zr,Nb)Fe-2. A remarkably isotropic ZTE is achieved with a negligible coefficientof thermal expansion (+0.47 x 10(-6) K-1) from 4 to 425 K, almost wider than most ZTE in metals available.A combined in situ magnetization, neutron powder diffraction, andhyperfine Mo''ssbauer spectrum analysis reveals that interplanarferromagnetic ordering contributes to a large magnetic compensationfor normal lattice contraction upon cooling. Trace Fe-doping introducesextra magnetic exchange interactions that distinctly enhance the ferromagnetismand magnetic ordering temperature, thus engendering such an ultrawideZTE. This work presents a promising ZTE in kagome metallic materials.