H. Dohnomae

Magnetoresistance of multilayers with two magnetic components

Abstract Multilayers consisting of Cu, Co, Cu and Ni(Fe) alloy layers were prepared and magnetoresistance (MR) properties were studied. In the magnetization process, a giant ferrimagnetic state is realized at moderate external fields because of the difference of the coercive fields in the two magnetic layers and then the resistance is greatly enhanced. MR properties were examined by varying the total layer number and the Cu layer thickness. The largest MR ratio was observed in [Cu(55 A)/Co(25 A)/Cu(55 A)/Ni 80 Fe 20 (25 A)]×15; 10% at 300 K and 28% at 80 K.

X-ray diffraction analysis of lattice strain in metallic superlattice films

Abstract In-plane lattice spacings of [Au(xA)/Ni(xA)] and [Pd(xA)/Cu(xA)] superlattice films with [111]fcc textures and large lattice misfits have been measured by X-ray diffraction. With decrease of superlattice period (Λ = 2x), Au and Pd layers are compressed whereas Ni and Cu layers are expanded. The observed lattice spacings (d220) of the individual layers vary almost linearly depending on 1/Λ. The lattice spacings of two constituent layers become equal in a Au/Ni superlattice with Λ = 8 A (d 220 = 1.371 A ) and a Pd/Cu superlattice with Λ = 14 A (d 220 = 1.337 A ) .

Structural and magnetic properties of Cr/Sb multilayers

Cr/Sb multilayered films take two types of structures - epitaxial superlattice and non-epitaxial multilayer - depending on the thickness of Cr layer (dCr) and substrate temperature during deposition (Ts). The epitaxial superlattices were formed when dCr ≤ 2A and Ts = 90°C; Cr and Sb reacted into a NiAs-type compound CrSb, and furthermore deposited Sb grew epitaxially on the CrSb layer. With other deposition parameters, non-epitaxial Cr/Sb multilayers were formed, in which Cr layers are polycrystalline or amorphous-like but Sb layers are crystalline and [00.1] oriented. The reactivities of Cr/Sb interfaces greatly affect the film quality. Magnetic properties are also dependent on the degree of compound formation. The epitaxial CrSb/Sb superlattices show a ferromagnetic feature at 5 K, whereas the non-epitaxial Cr/Sb multilayers show a paramagnetic feature.

197Au Mössbauer study of Au/Ni multilayers

Abstract 197 Au Mossbauer spectra have been measured for Au/Ni artificial multilayers. From the area ratio in a spectrum from a multilayer component and a component rising from pure Au buffer layer and its temperature dependence from 16 to 75 K, it is found that the Debye-Waller factor of Au in Au(10 A)/Ni(10 A) is larger than that of bulk Au, suggesting the existence of a supermodulus effect in this multilayer.

Structural and magnetic properties of 3d/Sb multilayers

Abstract Structures and magnetic properties of artificially prepared multilayers consisting of Sb and a 3d metal (Cr, Mn, Fe, Co or Ni) have been investigated. Obtained structures greatly depend on the reactivity between Sb and the metal. In the most reactive combination, Mn and Sb, ferromagnetic MnSb monolayers were prepared. An influence of substrate temperature on the multilayered structure is typically shown in the case of Cr and Sb.

Magnetic structure of CrSb/Sb superlattices

Abstract The ferromagnetic moment of CrSb/Sb superlattices originates in uncanceled magnetic moments of ultrathin antiferromagnetic CrSb layers. The existence of atomic steps should be taken into account to understand the magnetic properties.

Magnetic Properties and Magnetoresistance of Multilayers with Two Different Magnetic Layers

The spin-dependent electron scattering in multilayer films consisting of Cu and two magnetic materials, Co and Ni80Fe20 alloy, was investigated. In the magnetization process, a giant ferrimagnetic state is realized at moderate external field because of the difference in coercive forces. When the magnetizations of two ferromagnetic layers are antiparallel to each other, the electrical resistivity increases due to spin-dependent electron scattering. The MR ratio was observed to be 10% at room temperature and 28% at 80K in the multilayers film [Ni80Fe20 (25Å) /Cu (55Å)/Co (25å)/Cu (55Å)]×l5 film.

Analysis of magnetization process in Fe/GdFe multilayers

Abstract Magnetization processes of Fe/GdFe-alloy multilayers were investigated and an interlayer exchange interaction was revealed to contribute to these processes. Then the interlayer exchange interaction was controlled by inserting non-magnetic layers (Au or Cr) at each interface and the magnetic behavior was studied.