Interplay of itinerant magnetism and spin-glass behavior in FexCr1-x

When suppressing the itinerant antiferromagnetism in chromium by doping with the isostructural itinerant ferromagnet iron, a dome of spin-glass behavior emerges around a putative quantum critical point at an iron concentration x≈0.15. Here, we report a comprehensive investigation of polycrystalline samples of FexCr1-x in the range 0.05≤x≤0.30 using x-ray powder diffraction, magnetization, ac susceptibility, and neutron depolarization measurements, complemented by specific heat and electrical resistivity data for x=0.15. Besides antiferromagnetic (x<0.15) and ferromagnetic regimes (x≥0.15), we identify a dome of spin-glass behavior at low temperatures for 0.10≤x≤0.25. Neutron depolarization measurements indicate an increase of the size of ferromagnetic clusters with increasing x and the Mydosh parameter φ, inferred from the ac susceptibility, implies a crossover from cluster-glass to superparamagnetic behavior. Taken together, these findings consistently identify FexCr1-x as an itinerant-electron system that permits to study the evolution of spin-glass behavior of gradually varying character in an unchanged crystalline environment.