The magnetization of thin films of cobalt ferrite frequently falls far below the bulk value of 455 kAm -1 , which corresponds to an inverse cation distribution in the spinel structure with a significant orbital moment of about 0.6 µB that is associated with the octahedrally-coordinated Co 2+ ions. The orbital moment is responsible for the magnetostriction and magnetocrystalline anisotropy, and its sensitivity to imposed strain. We have systematically investigated the structure and magnetism of films produced by pulsed-laser deposition on different substrates (TiO2, MgO, MgAl2O4, SrTiO3, LSAT, LaAlO3) and as a function of temperature (500-700C) and oxygen pressure (10 -4 -10 Pa). Magnetization at room-temperature ranges from 60 to 440 kAm -1 , and uniaxial substrate-induced anisotropy ranges from +220 kJm -3 for films on deposited on MgO (100) to -2100 kJm -3 for films deposited on MgAl2O4 (100), where the roomtemperature anisotropy field reaches 14 T. No rearrangement of high-spin Fe 3+ and Co 2+ cations on tetrahedral and octahedral sites can reduce the magnetization below the bulk value, but a switch from Fe 3+ and Co 2+ to Fe 2+ and low-spin Co 3+ on octahedral sites will reduce the lowtemperature magnetization to 120 kAm -1 , and a consequent reduction of Curie temperature can bring the room-temperature value to near zero. Possible reasons for the appearance of low-spin cobalt in the thin films are discussed.

We used resonant inelastic x-ray scattering (RIXS) at the Ni L 3 edge to measure the dispersion of spin waves in NiO thin films along the [101], [001], and [111] directions. Samples with tensile and compressive in-plane strain show identical dispersion within the experimental uncertainty. The fitting of the data with a linear spin wave model applied to a three-dimensional Heisenberg antiferromagnetic lattice provides a leading superexchange parameter J = 18 meV. The magnon energy at the Brillouin zone boundary and the value of J are 5% smaller than those determined by inelastic neutron scattering on bulk single crystals. This discrepancy is likely induced by the strain or other structural differences between bulk and epitaxially grown samples. These results demonstrate the capabilities of high-resolution RIXS in the study of the magnetic structure of thin films and heterostructures for which neutron scattering is not sensitive enough.

Porous organosilicate glass thin films, with k-value 2.0, were exposed to 147 nm vacuum ultra-violet (VUV) photons emitted in a Xenon capacitive coupled plasma discharge. Strong methyl bond depletion was observed, concomitant with a significant increase of the bulk dielectric constant. This indicates that, besides reactive radical diffusion, photons emitted during plasma processing do impede dielectric properties and therefore need to be tackled appropriately during patterning and integration. The detrimental effect of VUV irradiation can be partly suppressed by stuffing the low-k porous matrix with proper sacrificial polymers showing high VUV absorption together with good thermal and VUV stability. In addition, the choice of an appropriate hard-mask, showing high VUV absorption, can minimize VUV damage. Particular processing conditions allow to minimize the fluence of photons to the substrate and lead to negligible VUV damage. For patterned structures, in order to reduce VUV damage in the bulk and on feature sidewalls, the combination of both pore stuffing/material densification and absorbing hard-mask is recommended, and/or the use of low VUV-emitting plasma discharge.

No abstract