Spectroscopic Study of the Magnetic Ground State of {{Nb}}_{1-y}{{Fe}}_{2+y}

We have investigated single crystals and polycrystals from the series Nb\$_\{1-y\}\$Fe\$_\{2+y\}\$, \$-0.004 $\backslash$leq y $\backslash$leq 0.018\$ by electron spin resonance, muon spin relaxation and M$\backslash$"ossbauer 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 (\$$\backslash$simeq 0.06 \textasciitilde$\backslash$mu_B/\{$\backslash$rm Fe\}\$), Nb--rich and stoichiometric NbFe\$_2\$ display spin density wave order with small magnetic moment amplitudes of the order \$$\backslash$sim 0.001 - 0.01 \textasciitilde$\backslash$mu_B/\{$\backslash$rm Fe\}\$. This provides microscopic evidence for a modulated magnetic state on the border of ferromagnetism in NbFe\$_2\$.     «

We have investigated single crystals and polycrystals from the series Nb\$_\{1-y\}\$Fe\$_\{2+y\}\$, \$-0.004 $\backslash$leq y $\backslash$leq 0.018\$ by electron spin resonance, muon spin relaxation and M$\backslash$"ossbauer 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 (\$$\backslash$simeq 0.06 \textasciitilde$\backslash$mu_B/\{$\backslash$rm Fe\}\$), N...     »