Magnetic properties of Ni/Cu/Ni epitaxial films with perpendicular anisotropy

Manifold domain structure of double films with perpendicular magnetic anisotropy

“…The remanent magnetization M r is close to one for all the M-H loops with H perpendicular to the plane as expected for a loop taken along an easy direction; meanwhile the in-plane loops display no significant values for M r . These findings indicate the presence of an effective magnetic anisotropy perpendicular to the film, being the value of K ef f about 90 kJ/m 3 for all the films presented in this work [14]. The sharp change in the value of M at the value of the coercive field H c indicates that the inversion of M proceeds with the propagation of domain walls previously nucleated.…”

“…Thus, we evaluate the variation of the elastic density energy if the magnetostrictive strain is allowed to exist in the Ni film by the formation of a set of i domains, each one with a volume v i and with M in the plane along <10> directions, see figure 4(c). Inside each domain, to the epitaxial strain components ε c 11 (2) Note that the more usual magneto-elastic corrections effects, that go with (ε me jj ) 2 , result negligible compared with the terms of Equation (2) due to the strong internal deformation, ε 0 that for our films is ε 0 ≈ 2.1 10 −2 [14], while ε me ii ∼-6 10 −5 [27]. The relationship between magnetostrictive strain ε me , irreducible deformations of the cubic lattice, orientation of M and the measurement direction is,…”

“…Epitaxial Cu (5nm)/Ni (3nm)/Cu (100 nm) and Cu (5nm)/Ni (3nm)/Cu (t Cu )/Ni (3nm)/Cu (100 nm) films with t Cu = 3.5 nm, 4 nm, 4.5 nm and 6 nm were grown on Si (001) wafers at room temperature by electron-beam evaporation in a chamber with a base pressure below 2 x 10 −10 Torr, using a procedure reported elsewhere [14]. Hysteresis loops and domain images of the samples were taken at room temperature using a vibrating sample magnetometer (VSM) and a magnetic force microscope (MFM), respectively.…”

“…For the Ni/Cu system ∆e release energy (∆e <0), since ε 0 ≈0.021 [14], and λ 100 is negative [27]. If ∆e were able to keep one of the magnetic layers with the domains in the film plane, it should overcome K ef f ≈ 90 10 3 J/m 3 .…”