Growth and interface magnetic anisotropy of epitaxial Mo/Fe/Mo(110) and W/Fe/W(110) ultrathin films

The literature provides numerous studies about W/Fe(110)/W epitaxial thin films, both concerning growth behavior and magnetic properties. However, only few data are available for the growth behavior of Mo/Fe(1 1 0)/Mo epitaxial thin films, and virtually nothing is known about their magnetic properties. We report here on W/Fe(110)/W and Mo/Fe(1 1 0)/Mo epitaxial thin films grown by pulsed laser deposition. The growth behavior, as investigated by means of RHEED, is found to be very similar to that reported for thermal deposition. In particular no growth difference is found between Mo- and W-based films. Besides, we complement the literature by providing for the thickness range 2-10 ML a growth procedure which we optimized in relation to magnetic coercivity measurements. As for magnetic anisotropy, and like it was already known to be the case for W-based films, we found for Mo/Fe films that the magnetization lies in plane (at feast for thickness t down to 4 ML), and that the anisotropy in-the-plane increases linearly with 1/t. The magnetization preferentially aligns along [0 0 1] at small thickness in the case of Mo/Fe/Mo, whereas it aligns along [1 (1) over bar 0] in the case of W/Fe/W films. Possible origins for the unexpected difference of behavior between these two systems are discussed. (C) 1999 Elsevier Science B.V. All rights reserved.