Ferromagnetism in the thermodynamically stable monolayer Fe(110) on W(110), coated by Ag

Ferromagnetic order in the thermodynamically stable, pseudomorphic monolayer Fe(110) on W(110), coated by Ag, was studied in situ in UHV using Conversion Electron Mössbauer Spectroscopy (CEMS) and Torsion Oscillation Magnetometry (TOM). Films near the monolayer coverage, prepared at 475 K, consist of nearly independent monolayer and double-layer patches. The properties of monolayer patches are nearly independent of the mean film thickness resulting in excellent conditions to determine the true monolayer properties. The Curie temperature is reduced toT _{c, mono}= 282 K = 0.27 T_c,bulk, the ground state hyperfine field is reduced toB _hf(0)=11.9 T = 0.35B _hf,bulk(0) and the magnetic moment per atom is enhanced to(0) = 2.53 _B=1.14(0)_bulk. Remanent magnetization is detected forT 260 K=0.92T _{c, mono}, square loop magnetization forT 230 K=0.82T _{c, mono}. Unusual properties of the phase transition are detected by the combination of both experimental techniques.