A revisit to ultrathin NiO(001) film: LEED and valence band photoemission studies

Magnetic coupling across the antiferromagnetic–antiferromagnetic interface

“…We observe a progressive increase in the intensities of Co 2p and O 1s with the increase of CoO coverages while the intensities of Ni 2p and Ag 3d show a decrease in intensities, as expected. The observed core level lineshapes, as well as their binding energies for the different core levels, are found to be in good agreement with that of stoichiometric NiO [46] and CoO [47] epitaxial ultrathin films for different film coverages. Moreover, the same instrumental setup, growth parameters, and procedures as earlier works [46,47], have been used to grow the present NiO and CoO films.…”

“…The observed core level lineshapes, as well as their binding energies for the different core levels, are found to be in good agreement with that of stoichiometric NiO [46] and CoO [47] epitaxial ultrathin films for different film coverages. Moreover, the same instrumental setup, growth parameters, and procedures as earlier works [46,47], have been used to grow the present NiO and CoO films.…”

“…The NiO films also show the same p(1 × 1) pattern as Ag(001) substrate, confirming the strained epitaxy in these films. However, the LEED spots become broader with increased NiO film thickness, due to the increased mosaicity of the film [46]. Interestingly, while decreasing the electron beam energy at RT, we observe four extra p(2 × 2) spots of weak intensity at [1/2, 0] position (see figure 1(g) for 23 eV beam energy).…”

“…Sample temperature was measured using a K-type thermocouple, in contact with the Ag crystal. The CoO and NiO layers were prepared in situ by reactive deposition of metallic Co and Ni in a directed oxygen partial pressure of 1 × 10 −6 mbar at a sample temperature of 473 K [46,47]. The deposition rate was calibrated using a water-cooled quartz crystal thickness monitor, mounted on a linear drive that could move to the sample position to measure the actual growth rate.…”

Antiferromagnetism of CoO-NiO bilayers studied by XMLD spectroscopy

“…The MgO(001) single-crystal substrate was ex-situ cleaved just before inserting into UHV and annealed at 573 K for 30 min to clean the surface. Both CoO and NiO layers were prepared in situ by deposition of metallic Co and Ni in a directed oxygen partial pressure of 1 × 10 −6 mbar at a sample temperature of 473 K [36,37]. High purity metals (99.995%) Ni and Co were evaporated from an e-beam evaporator and a hightemperature effusion cell, with a constant rate of 0.4 Å min −1 and 0.2 Å min −1 , respectively.…”