Experimental Exchange-Split Energy-Band Dispersions for Fe, Co, and Ni

Abstract

Using angle-resolved photoemission with single-crystal Fe(111) and Co(0001), we have determined accurate exchange-split energy-band dispersions $E(\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}})$ along symmetry lines. For Fe, Co, and Ni, respectively, occupied $d$-band widths are 3.1 eV ($P$), 3.8 eV ($L$), and 3.4 eV ($L, X$), while exchange splittings are \ensuremath{\sim}1.5 eV ($P$), \ensuremath{\sim}1.1 eV ($\ensuremath{\Gamma}$), and 0.3 eV (near $L$). Comparison with theory shows that state-of-the-art ab initio calculations describe the strong ferromagnets Fe and Co much better than Ni.