Evidence for Kondo effect in Zn:Fe

Zn films doped with $^{57}$Fe (atomic concentration c between 0.2 and 2.0 at \%) have been prepared by the co-evaporation of the two metals onto a cooled substrate ($\rm T_s$ = 80 K). \emph{In- situ} electrical resistance measurements on these films show resistance minima at $\rm T_K$ ($\rm T_K$ = 10 K for c = 1.0 at \%) which disappear in an external magnetic field $\rm B_{ex}$ = 5 T and, therefore, are interpreted as Kondo minima. $^{57}$Fe M\"{o} ssbauer effect studies on the films with c = 0.6 at \% taken at T = 4.3 K and for various $\rm B_{ex}$ values, reveal that the effective paramagnetic Fe moments, $\mu$, are $\mu$ $<$ 0.1 $\mu_{B}$ for $\rm B_{ex}$ $=$ 3 T. For larger magnetic fields the magnitude of $\mu$ is increasing with increasing $\rm B_{ex}$ [$\mu$ $\sim$ 0.30(3) $\mu_{B}$ for $\rm B_{ex}$ = 7 T], as expected for a spin-compensated Kondo state.