•N-type NiCo2O4-δ epitaxial thin films are prepared by RF sputtering method.•The deposition pressure dependent electrical properties have been investigated.•The maximum conductivity of 178 S/cm is obtained in 75 Pa deposited thin films.NiCo2O4-δ (NCO) epitaxial thin films have been grown on MgAl2O4(0 0 1) substrates at different Ar/O2(1:1) pressure by RF sputtering technique. HRXRD study indicates best crystalline quality and smallest unit cell volume are obtained in NCO thin films deposited at 75 Pa. Hall measurement reveals NCO thin films are of n-type conductivity with the electron mobility and electron density of NCO films in the range of 0.09–1.05 cm2/Vs and 1.06–5.94 × 1021 cm−3, respectively. Maximum conductivity of 178 S/cm is obtained in NCO thin films deposited at 75 Pa, which surpasses the conductivity of NCO films grown by using PLD method. XPS spectra confirm mixed valence states for nickel and cobalt ions, and existence of oxygen vacancies which triggers n-type conductivity. The deposition pressure dependent carrier density and unit cell volume are closely related to the concentration of oxygen vacancies.

Copper ferrite polycrystalline samples with different cation distributions are prepared via different thermal treatments. Combined studies including X-ray diffraction, PPMS, Mössbauer spectroscopy, and complex impedance spectroscopy show both conductivity and magnetism keep increasing, accompanied by an obvious phase transition from tetragonal symmetry (I41/amd) to cubic symmetry (Fdm) as Cu2+ ions migrate from Oh sites to Td sites. The changes of structural, electrical and magnetic properties due to the cation redistribution are also investigated by spin-polarized density functional theory. The simulated results indicate that the semiconducting band structure gradually transforms into a metallic band structure as Cu2+ ions migrate from Oh sites to Td sites. The conductivity and magnetism will increase during the same process, which matches well with the experimental observations. This work demonstrates that the cation redistribution in copper ferrite is effective in controlling both conductivity and magnetism, which can be further exploited in applications using interacting electron/spin systems.

Epitaxial LiFe5O8 thin films with various thicknesses were fabricated on (001) MgAl2O4 substrates by using a high-pressure sputtering system. All the LiFe5O8 thin films have excellent epitaxial quality with ordered α-LiFe5O8 structure, and larger in-plane compressive and out-of-plane tensile strain can be obtained by decreasing the film thickness. Moreover, the in-plane compressive strain can significantly induce the enhancement of in-plane magnetization while the out-of-plane tensile strain tends to reduce the out-of-plane magnetization. It indicates that controlling the thickness of the films is an effective method to tailor the interface strain and further modify the magnetic properties of the epitaxial LiFe5O8 thin films.

LiFe5O8 epitaxial thin films with high crystalline quality have been successfully synthesized on (001) MgAl2O4 substrates even at an ultra-low working temperature of 200 °C by using a high-pressure radio-frequency sputtering system. Better crystalline qualities of the epitaxial LiFe5O8 films can be obtained with an increase of the deposition temperature in the range from 200 °C to 800 °C. Moreover, the growth temperature can significantly affect the magnetic properties of the LiFe5O8 thin films. The strain states, crystalline quality and defect density should be the main causes for the tunable magnetic properties. Overall, the wide-temperature range processing window, especially the low deposition temperature of 200 °C, of the LiFe5O8 films by this method will offer flexibilities for direct integration with semiconductors, organic electronics, flexible electronic materials and other related elements which are sensitive to the processing temperature.

Lead-free (Na0.5Bi0.5)0.95Ba0.05TiO3 (0.95NBT–0.05BT) thin films were deposited on polycrystalline Ni substrates by using the RF high-pressure sputtering system. Microstructural studies by high resolution X-ray diffraction reveal that the as-deposited 0.95NBT–0.05BT thin films are polycrystalline structures. The piezoelectric property measurements by a piezoresponse force microscopy exhibit that the polycrystalline 0.95NBT–0.05BT thin films have an excellent piezoelectric response. It is indicated that the as-grown 0.95NBT–0.05BT thin films have the potential for the development of the structural health monitoring systems and related device applications.

Thin films of double-perovskite structural LaBaCo2O5.5+δ were epitaxially grown on (110) NdGaO3 substrates by pulsed laser deposition. Microstructural studies by high-resolution X-ray diffraction and transmission electron microscopy revealed that the films have an excellent quality epitaxial structure. In addition, strong in-plane anisotropic strains were measured. Electrical transport properties of the films were characterized by an ultra-high-vacuum four-probe scanning tunneling microscopy system at different temperatures. It was found that the anisotropic in-plane strain can significantly tune the values of film resistance up to 590%.Keywords: anisotropic; interface; LaBaCo2O6; thin film; transport properties;

•ZnO/Ag nanocomposite films have been fabricated by reactive radio-frequency magnetron sputtering system.•Ag nano-particles are uniformly embedded into the ZnO/Ag nanocomposite films.•The films exhibit strong intensities reduction of the reflection spectra in UV and visible region.•The films exhibit strong intensities enhancement of resonance Raman scattering spectra.Self-assembled ZnO/Ag nanocomposite thin films have been fabricated on Si (111) by a reactive radio-frequency magnetron sputtering system. Microstructural characterizations by transmission electron microscopy indicated that the Ag nano-particles are uniformly embedded into the ZnO films. The intensity of resonance Raman scattering spectra is significantly enhanced with the increase of Ag contents in the film, compared with the pure ZnO film, while the intensity of reflection spectrum is reduced, which is assigned to the interaction between localized Surface Plasmons in the Ag nanoparticles and the incident light.

•Perovskite cobaltates LaBaCo2O5.5+δ thin films were directly integrated onto (001) Si substrates by pulsed laser deposition.•The polycrystalline LaBaCo2O5.5+δ films exhibit a largest magnetoresistance value of 18% at ~40 K•Similar magnetic behavior as its bulk materials of nanoscale ordered LaBaCo2O6 and larger magnetic moments and magnetic coercive field than the single-crystal LaBaCo2O5.5+δ films.Perovskite cobaltates LaBaCo2O5.5+δ thin films were directly integrated onto (001) Si substrates by pulsed laser deposition. Microstructural studies from X-ray diffraction reveal that the LaBaCo2O5.5+δ films are polycrystalline. Electrical transport property measurements indicate that the polycrystalline LaBaCo2O5.5+δ films have a semiconductor behavior with a largest magnetoresistance value of 18% at ~40 K. Magnetization property measurements show that the polycrystalline films exhibit magnetic behavior similar to its bulk materials of nanoscale ordered LaBaCo2O6 and have larger magnetic moments and magnetic coercive field than the single-crystal LaBaCo2O5.5+δ films.

Epitaxial LiFe5O8 thin films with various thicknesses were fabricated on (001) MgAl2O4 substrates by using a high-pressure sputtering system. All the LiFe5O8 thin films have excellent epitaxial quality with ordered α-LiFe5O8 structure, and larger in-plane compressive and out-of-plane tensile strain can be obtained by decreasing the film thickness. Moreover, the in-plane compressive strain can significantly induce the enhancement of in-plane magnetization while the out-of-plane tensile strain tends to reduce the out-of-plane magnetization. It indicates that controlling the thickness of the films is an effective method to tailor the interface strain and further modify the magnetic properties of the epitaxial LiFe5O8 thin films.