5d metals are used in electronics because of their high spin-orbit coupling (SOC) leading to efficient spin-electric conversion. When C60 is grown on a metal, the electronic structure is altered due to hybridisation and charge transfer. In this work we measure the spin Hall magnetoresistance for Pt/C60 and Ta/C60, finding they are up to a factor 6 higher than for the pristine metals, indicating an increase in spin Hall angle of 20-60%. At low fields of 1-30 mT the presence of the C60 increased the anisotropic magnetoresistance by up to 700%. Our measurements are supported by non-collinear Density Functional Theory calculations, which predict a significant SOC enhancement by C60 that penetrates through the Pt layer, concomitant with trends in the magnetic moment of transport electrons acquired via SOC and symmetry breaking. The charge transfer and hybridisation between the metal and the C60 can be controlled by gating, so our results indicate the possibility of dynamically modifying the SOC of thin metals using molecular layers. This could be exploited in spin transfer torque memories and pure spin current circuits.

This work reports the fabrication of titanium dioxide (TiO2) nanoparticle (NPs) films using a scalable drop-casting method followed by ultra-violet (UV) irradiation for creating defective oxygen vacancies on the surface of a fabricated TiO2 semiconductor film using an UV lamp with a wavelength oof 255 nm for 3 h. The success of the use of the proposed scalable strategy to fabricate oxygen-vacancy-rich TiO2 films was assessed through UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The Ti 2p XPS spectra acquired from the UV-treated sample showed the presence of additional Ti3+ ions compared with the untreated sample, which contained only Ti4+ ions. The band gap of the untreated TiO2 film was reduced from 3.2 to 2.95 eV after UV exposure due to the created oxygen vacancies, as evident from the presence of Ti3+ ions. Radiation exposure has no significant influence on sample morphology and peak pattern, as revealed by the SEM and XRD analyses, respectively. Furthermore, the photocatalytic activity of the fabricated TiO2 films for methylene-blue-dye removal was found to be 99% for the UV-treated TiO2 films and compared with untreated TiO2 film, which demonstrated only 77% at the same operating conditions under natural-sunlight irradiation. The proposed UV-radiation method of oxygen vacancy has the potential to promote the wider application of photo-catalytic TiO2 semiconductor films under visible-light irradiation for solving many environmental and energy-crisis challenges for many industrial and technological applications.

Magnetic multilayers with perpendicular anisotropy and an interfacial Dzyaloshinskii-Moriya interaction contain chiral domain walls and skyrmions that are promising for applications. Here we measure the temperature dependence of the Dzyaloshinskii-Moriya interaction (DMI) in Pt/CoFeB/Ir and Pt/CoB/Ir multilayers by means of static domain imaging. First, the temperature dependences of saturation magnetization (MS), exchange stiffness (A) and intrinsic perpendicular anisotropy (Ku) are determined. Then the demagnetized domain pattern in each multilayer is imaged by wide-field Kerr microscopy in the temperature range 9-290 K, and the characteristic domain period at each temperature is determined. We calculate the DMI constant D from an analytical expression for the domain wall energy density that treats the multilayer as a uniform medium. Scaling laws for Ku and D with the magnetization are established from the experiments. While the scaling of Ku is consistent with Callen-Callen theory, we find that the scaling of D is similar to that of A predicted theoretically (∼ 1.8).