Fig. 1. Schematic representation of the main effects induced by the FM–AFM exchange coupling, i.e., (a) loop shift, (b) coercivity enhancement and (c) unidirectional anisotropy.

Fig. 2. Schematic diagram of the spin configurations of a FM–AFM couple before and after the field cooling procedure [4].

Fig. 3. Schematic diagram of the spin configurations of an FM–AFM couple at the different stages of a shifted hysteresis loop for a system with large K_AFM [4].

Fig. 4. Schematic diagram of the spin configurations of a FM–AFM bilayer, at the different stages for a system with small K_AFM.

Fig. 5. Sketch and examples of the different types of lithographed nanostructures described in the text (a) Type Ia and Ib—patterned AFM–FM or FM–AFM nanostructures: (b) IrMn–CoFe dots [201] and Ni–NiO lines [199]; (c) Type II—patterned FM nanostructures on a continuous AFM layer: (d) Fe dots on a continuous FeF₂ film [204]; (e) Type III patterned AFM nanostructures on a continuous FM layer: (f) FeMn lines on a FeNi continuous film [177] and (g) Type IV—surface oxidized (AFM) FM nanostructures: (h) Oxidized Co dots [218].

Fig. 6. Dependence of the loop shift, H_E, at different temperatures on the wire width, W, for (a) Fe₁₉Ni₈₁–NiO [181] and (b) Ni–NiO [199], Type I structures, evidencing the contradicting tendencies with W. Note the two different types of x-axis.

Fig. 7. Hysteresis loops at after field cooling in , for Type II Fe lines on FeF₂, for three patterns with the lines +45 (a, d), 0 (b, e), and -45 (c, f) oriented with respect to the cooling field and the applied field during the hysteresis loop measurements. The applied magnetic field is parallel to the cooling field for (a)–(c), while it is perpendicular to it for (d)–(f). The directions of the applied field and cooling field with respect to the lines are indicated to the right of each plot [196].

Fig. 8. (a) Hysteresis loops of Type II Fe nanodot arrays (60 nm diameter, 15 nm thick) on MgO (unbiased, open symbols) and on a 90-nm-thick FeF₂ film (exchange biased, solid symbols) at , after field cooling in 5 kOe from 300 K. Shown in (b) is a scanning electron microscopy image of the structure of the sample [204].

Fig. 9. Schematic drawing of a system with (a) AFM antidots on a continuous FM layer, (b) FM antidots on a continuous AFM layer and (c) AFM–FM antidots.

Fig. 10. (a) Schematic drawing of a core–shell structure and (b) transmission electron microscopy (TEM) image of an oxidized Co particle.

Fig. 11. Hysteresis loop of Co–CoO oxidized core–shell nanoparticles at after zero field cooling (ZFC, open symbols) and after field cooling in (FC, solid symbols) [301].

Fig. 12. Schematic representation of (a) a nanoparticle (FM)—matrix (AFM) nanocomposite and (b) FM nanoparticles on an AFM surface.

Fig. 13. (a) Temperature dependence of the remanent moment, m_R, for Co–CoO oxidized core–shell nanoparticles embedded in a non-magnetic Al₂O₃ matrix (open symbols) and in an AFM CoO matrix (solid symbols). The superparamagnetic blocking temperatures of both systems are indicated in the figure. (b) TEM images of the microstructure of the sample [82].

Fig. 14. (a) Scanning electron microscopy micrograph of ball milled Co–NiO powders. (b) Temperature dependence of the loop shift, H_E(T), after field cooling in [428] and [430].

Fig. 15. (a) Transmission electron microscopy micrograph of Fe nanoparticles embedded in a Cr₂O₃ matrix. Temperature dependence of (b) the loop shift, H_E and (c) the coercivity, H_C, for Fe nanoparticles embedded in a Cr₂O₃ matrix after field cooling in [487].

Fig. 16. Dependence of (a) the loop shift, H_E, and (b) the coercivity, H_C, on the amount of CoO shell for a SrFe₁₂O₁₉–CoO core–shell nanoparticle at [503].

Fig. 17. Calculated spin structure of a 4 nm NiFe₂O₄ nanoparticle in an applied field of [551].

Fig. 18. Schematic representation of typical (a) spin valve devices with metallic–non-magnetic interlayers, e.g., Cu and (b) tunnel magnetoresistance devices with insulating–non-magnetic interlayers, e.g., Al₂O₃. Depicted in (c) is a characteristic magnetoresistance curve for this type of systems, where the magnetization direction of the layers is indicated.

Fig. 19. Cross-sectional TEM image of a cell in a MRAM memory. The cell is separated between the magnetic part (MRAM BEOL) and the electronic part (CMOS FEOL). The bit line and word line, used to write and read information are shown in the image. The magnetic tunnel junction is highlighted by a circle. Image courtesy of Freescale Semiconductors.

Exchange bias blocking temperature and the maximum reported loop shifts for some ferrite and manganite nanoparticles

Note that the given values are not necessarily at the same temperatures, for the same cooling fields or for the same nanoparticle diameters, and are thus not readily comparable.

Exchange bias blocking temperature and the maximum reported loop shifts for some antiferromagnetic nanoparticles

Note that the given values are not necessarily at the same temperatures, for the same cooling fields or for the same nanoparticle diameters, and are thus not readily comparable.

Characteristic length scales: exchange length (l_ex), domain wall width (πδ_o), critical single domain size for a sphere (R_SD) for some ferromagnetic materials estimated using bulk parameters [48], [56], [58], [758], [765], [766] and [767]

Estimated domain wall width, πδ_o,AFM, for some antiferromagnets assuming bulk parameters [726], [768], [769], [770], [771] and [772]