No abstract

We have carried out studies of the interfacial roughness of a number of Nb/a-Si multilayers using cross-section transmission electron microscopy, wide-angle x-ray diffraction, and low-angle x-ray reflectivity and diffuse scattering. The multilayers studied were grown by sputtering in an Ar atmosphere at various pressures. The effect of the layer thickness and of the number of layers has also been studied. We observed a clear transition in the growth morphology when the sputtering pressure is raised above the thermalization pressure ( =9 mTorr) of the sputtered atoms. Both the mosaic of the Nb crystallites and the interface roughness increase dramatically when the Ar pressure exceeds 9 mTorr. The roughness of the various interfaces is strongly conformal and the samples with large roughness show a roughness that increases with deposited layer number. We discuss the quantitative extraction of these parameters from the x-ray data and the implications of these results for the physics of the deposition process.

The Neel temperature (Tz) of Cr in sputtered, epitaxial Fe/Cr(001) superlattices is identified via transport and magnetic anomalies.The onset of the antiferromagnetism is at a thickness tc, of 42 A. The bulk value of Tz is approached asymptotically as tc, increases and is characterized by a three-dimensional shift exponent. Most strikingly, the biquadratic interlayer magnetic coupling (90 orientation of adjacent Fe layers), observed in the thick Cr regime, is suppressed below T~These. results are attributed to finite-size effects and spin frustration near rough Fe-Cr interfaces.PACS numbers: 75.70.Fr, 73.50.Jt, 75.30.Kz, 75.50.Rr Fe/Cr superlattices exhibit a variety of intriguing magnetic properties, including oscillatory interlayer coupling

An epitaxial orientation of Fe/Cr superlattices -Fe/Cr(211) on MgO(110)is grown by magnetron sputtering.Its structural and magnetic characterizations are presented and compared to those for Fe/Cr(100) superlattices grown simultaneously onto MgO(100) substrates. The epitaxial orientation of the Fe/Cr (211) superlattices is Fe/Cr[011]~iMgO[001] and Fe/Cr[111]iiMgO[110], while that for Fe/Cr(100) is Fe/Cr[001]~~MgO[011]. A uniaxial, in-plane surface anisotropy for the Fe/Cr(211) superlattices along the Fe[011]of 0.06 erg/cm2 is obtained from analysis of the magnetization hysteresis loops.Four oscillations in the antiferromagnetic interlayer coupling and giant magnetoresistance (CiMR) are 0 observed with a period of 18 A for both orientations. The strength, oscillation period, and phase of the magnetic coupling are identical for the two orientations. The GMR values increase by a factor of -4 to 5 on cooling from room temperature to 4.2 K. At 4.2 K the maximum GMR value of the [Fe(14 A)/Cr(8 A)],0 superlattice is 70% for the (211) orientation and 150% for the (100) orientation.

We present structural and magnetic properties of epitaxial Sm–Co/Co superlattice films prepared via magnetron sputtering. X-ray diffraction and cross-sectional transmission electron microscopy show that the films are structurally coherent. The oriented nature of the interleaved ferromagnetically “hard” and “soft” layers comprising the superlattice provides a realization of the ideal nanostructure of exchange-spring magnets as well as a model system to study layer thickness dependences of the magnetic properties. The superlattice films have an effective fourfold, in-plane magnetic anisotropy. Room-temperature hysteresis loops are relatively square and the demagnetization of the Co is reversible, as expected of exchange-spring magnets with aligned hard magnet layers.