Structure, morphology and magnetism of an ultra-thin [NiO/CoO]/PtCo bilayer with perpendicular exchange bias

Abstract

Electronic and magnetic properties of nanoscale materials are closely related to the atomic arrangement at the interface shared by different chemical elements. A very precise knowledge of the surface/interface structure is then essential to properly interpret the new properties coming out. Of a particular interest is the relationship between structure, morphology and magnetic properties of exchanged-coupled interfaces in ferromagnetic (FM) and antiferromagnetic (AF) materials. The interaction at the AF/FM interface modifies the magnetic switching properties of the FM film, which turn out to be a usefull property on new magnetic devices technology. We present here an investigation of the buried exchange-coupled interface [NiO/CoO]/[PtCo] grown on a Pt(111) single crystal. The magneto-optical Kerr effect reveals a strong coupling at the interface, by an increasing coercivity, and a spin reorientation of the FM film when ordering occurs in the AF layer. The combination of grazing incidence X-ray diffraction, X-ray reflectivity and soft X-ray resonant magnetic scattering yields a comprehensive description of the system.

Concentration- and thickness-dependent magnetic properties of NixMn100−xin epitaxially grown NixMn100−x/Ni/(Co/)Cu3Au(001)

“…For a large AFM anisotropy at lower temperatures and lower Ni concentrations in our proposed model, the FM layer decouples from part of the AFM layer because it cannot drag the AFM pinned spins, consequently an exchange bias effect comes into action while reducing H C . A result of the influence of this effect on H C is the peak which is often found close to T b [8,28,[41][42][43]]. In our system (figure 2(a)), when the anisotropy of the AFM decreases, either due to increasing temperature or increasing Ni concentration, the FM is able to drag more and more AFM spins, thus increasing the coercivity.…”

Impact of orthogonal exchange coupling on magnetic anisotropy in antiferromagnetic oxides/ferromagnetic systems

“…Important is the fact that, for these three AFOs, T N changes drastically. Oxidation before deposition of CoO results in remarkably increased Néel temper ature since the Néel temperature of thick NiO is equal to 525 K [40,41]. Moreover, in [NiO/CoO] N superlattices, T N enhancement has been confirmed by neutron diffraction and heat capacity measurements [39,42].…”

Probing antiferromagnetism in NiMn/Ni/(Co)/Cu3Au(001) single-crystalline epitaxial thin films

“…This behavior has been observed for several other systems. [24][25][26][27] Both, the H eb value and the blocking temperature T b , the latter indicated by black arrows in Fig. 5, are slightly higher in the case of NiMn coupled to OoP Ni than in the IP case.…”