First principles studies of Fe/Co superlattices and multilayers with bcc (001) and (110) orientations

Crystallographic input data for (001)-, (110)- and (111)-oriented superlattices

“…They can be generated artificially during the growth process but they can also occur naturally since a change of orientation can be induced by temperature or pressure (Sutrakar et al, 2012). The study of the orientation effect on superlattices and/ or quantum wells is a well documented topic and is still of actuality and importance (Kajikawa, 2012;Assa Aravindh et al, 2012). The presence of built-in permanent piezoelectric fields in (111)-and (311)-oriented superlattices (SLs) and the progress in crystal growth processes have renewed the interest in these systems due to the potential they present for nanophononics which manipulates sound and heat at the nanoscale (acoustic phonons of gigahertz-terahertz frequencies and nanometer wavelengths; Reparaz et al, 2010;Rozas et al, 2005Rozas et al, , 2008Mintairov & Melehin, 1999;Lambert & Srivastava, 1999).…”

“…To our knowledge the problem of SLs with various growthaxis directions has often been addressed by means of the envelope function approach (Kajikawa, 2012;Los et al, 1995;Hayakawa, Suyama et al, 1998a,b;Hayakawa, Takahashi, Kondo et al, 1988a,b;Haya-kawa, Takahashi, Suyama et al, 1988;Vina & Wang, 1986;El Khalifi et al, 1990;Gil et al, 1990) and rarely by other methods such as the tight-binding approach (Wang & Ting, 1995) or the first-principles methods (Assa Aravindh et al, 2012;Rubio et al, 1994;Picozzi et al, 1997;Magri, 1990;Bungaro & Rabe, 2002;Tair et al, 2007;Badi et al, 2008). The first-principles methods are particularly needed to investigate microscopically these specific systems.…”

Structural, magnetic and electronic properties of two dimensional NdN: an ab initio study

“…The aforementioned variation in MAE with layer thickness was analyzed in relation to the anisotropy of orbital moments. These two anisotropies are interrelated by Bruno's rule, [29][30][31] according to which the difference in orbital moments along two different orientations is given as by Dm L ¼ L para À L perp . The orbital moments pertaining to layers of different thickness reported in Table 2 indicate that their values are greater along the perpendicular orientation (L perp ) for the 0.25 nm lm only.…”

From Termination Dependent Chemical Sensitivity of Spin Orientation in All-bcc Fe/Co Magnetic Superlattices toward the Concept of an Artificial Surface of a Ferromagnet

“… 30 Consequently, the critical SRT thickness, which for uncovered Fe(110) films varies from 60 Å up to 130 Å depending on the preparation recipe, was drastically lowered (down to ∼10 Å) in the case of Au/Fe bilayers and moderately modified by adsorption of gases on the surface. On the other hand, using metastable bcc Co overlayers leads to a large increase of magnetic surface anisotropy and critical SRT thickness in Co(110)/Fe(110) bilayers, 31 which suggests that the increasing number of Fe/Co interfaces 32 , 33 in the system can further increase SMA and critical thickness of SRT. This can be experimentally realized by preparing epitaxial (Fe/Co) N multilayers on the surface of a bulk-like Fe(110) ferromagnetic film.…”

“…The total energy difference between these two orientations was next calculated and defined as the magnetic anisotropy energy (MAE = E X – E Y ). 33 From this definition, a negative MAE implies an easy axis along the X direction and positive MAE indicates that the Y axis is the easy axis. Table 1 presents the results of MAE calculations for (i) an UHV surrounded bilayer and in the case of (ii) H atoms or (iii) CO molecules attached either to Co or to an Fe terminated bilayer surface.…”