We have investigated single crystals and polycrystals from the series Nb1-yFe2+y, -0.004$\leq$y$\leq$0.018, by electron spin resonance, muon spin relaxation, and M̈ossbauer spectroscopy. Our data establish that at lowest temperatures all samples exhibit bulk magnetic order. Slight Fe excess induces low-moment ferromagnetism, consistent with bulk magnetometry, while Nb-rich and stoichiometric NbFe2 display spin density wave order with small magnetic moment amplitudes of order $\sim$0.001\textendash{}0.01$\mu$B/Fe. This provides microscopic evidence for a modulated magnetic state on the border of ferromagnetism in NbFe2.     «

We have investigated single crystals and polycrystals from the series Nb1-yFe2+y, -0.004$\leq$y$\leq$0.018, by electron spin resonance, muon spin relaxation, and M̈ossbauer spectroscopy. Our data establish that at lowest temperatures all samples exhibit bulk magnetic order. Slight Fe excess induces low-moment ferromagnetism, consistent with bulk magnetometry, while Nb-rich and stoichiometric NbFe2 display spin density wave order with small magnetic moment amplitudes of order $\sim$0.001\textenda...     »