Structural, elastic, and transport anomalies in molybdenum/nickel superlattices

Abstract

Metallic superlattices of nickel and molybdenum have been synthesized for a wide range of layer thicknesses by alternate sputtering. X-ray examination shows that they are composed of layers of fcc nickel and bcc molybdenum oriented along [111]and [110]directions, respectively. Anomalies have been observed in the lattice spacings, elastic moduli, and electrical resistivity versus modulation wavelength. These anomalies occur simultaneously at the same superlattice wavelength. The anomalies have been interpreted as due to strains in the nickel lattice.

In-plane uniaxial magnetic anisotropy induced by anisotropic strain relaxation in high lattice-mismatched Dy/Sc superlattices

“…For instance, for the (Dy 20 /Sc 60 ) 50 SL, we calculate that for the Dy layers, the average in-plane strain is ε = −0.0231 and the out-of-plane strain is ε ⊥ = 0.0256. Notice that, as found in other systems [57], ε ⊥ > |ε | in opposition to the Poisson's ratio [58], i.e., ε ⊥ = −2ε c 13 c 33 , where c 13 /c 33 (=0.263 [59]) is taken as the bulk value. Apparently, the origin of the anomalous strains in multilayered systems seems to be related to the electronic band mismatching [60] (dissimilar Fermi energy and/or electronic band structure) between constituents and, therefore, it is difficult to accurately separate out from the epitaxial strains.…”

Characterization of thermally stable W/Ni multilayers by X-rays and cross-sectional transmission electron microscopy

“…For metallic MLS with bilayer of equal thickness of individual metal (W/Mo, Ni) layers, superlattice peaks appear about W/Mo(110) and Ni(111) both [5][6][7][8][9]. In these MLS superlattice formation takes place due to alignment of the crystallographic planes of these metals parallel to the interface.…”

“…Occurrence of these elastic anomalies has been experimentally well evidenced by surface velocity measurement in Brillouin scattering experiments [3,4]. In this regard metallic superlattices having equal layer thickness of metal combinations like Mo/Ni, W/Ni and W/ Cu have been studied [5][6][7][8][9][10]. Yet another important class of superlattices is found in epitaxially grown semiconducting multilayers like Ge x Si 1 − x /Si.…”

Surface Wave Velocity of Silver/Chromium and Gold/Chromium Superlattices

“…An unexpected decrease of the Rayleigh wave velocity (softening of the elastic constants) has been reported for Nb/Cu[l], Mo/Ni [2], Ni/V [3] and Ag/Cr [4]. Au/Cr superlattices are the only exception to date to show a maximum in surface wave velocity as a function of the bilayer thickness [5].…”