We present measurements of the superconducting and charge-density-wave (CDW) critical temperatures (T c and T CDW ) as a function of pressure in the transition metal dichalchogenides 2H -TaSe 2 and 2H -TaS 2 . Resistance and susceptibility measurements show that T c increases from temperatures below 1 K up to 8.5 K at 9.5 GPa in 2H -TaS 2 and 8.2 K at 23 GPa in 2H -TaSe 2 . We observe a kink in the pressure dependence of T CDW at about 4 GPa that we attribute to the lock-in transition from incommensurate CDW to commensurate CDW. Above this pressure, the commensurate T CDW slowly decreases, coexisting with superconductivity within our full pressure range.

We present measurements of the superconducting critical temperature T c and upper critical field H c2 as a function of pressure in the transition metal dichalcogenide 2H -NbS 2 up to 20 GPa. We observe that T c increases smoothly from 6 K at ambient pressure to about 8.9 K at 20 GPa. This range of increase is comparable to the one found previously in 2H -NbSe 2 . The temperature dependence of the upper critical field H c2 (T ) of 2H -NbS 2 varies considerably when increasing the pressure. At low pressures, H c2 (0) decreases, and at higher pressures both T c and H c2 (0) increase simultaneously. This points out that there are pressure induced changes of the Fermi surface, which we analyze in terms of a simplified two-band approach.

We report a characterization of surfaces of the dichalcogenide TaSe 2 using scanning tunneling microscopy and spectroscopy at 150 mK. When the top layer has the 2H structure and the layer immediately below the 1T structure, we find a singular spatial dependence of the tunneling conductance below 1 K, changing from a zero-bias peak on top of Se atoms to a gap in between Se atoms. The zero-bias peak is additionally modulated by the commensurate 3a 0 × 3a 0 charge-density wave of 2H -TaSe 2 . Multilayers of 2H -TaSe 2 show a spatially homogeneous superconducting gap with a critical temperature also of 1 K. We discuss possible origins for the peculiar tunneling conductance in single layers.

Antireflective transparent materials are essential for a myriad of applications to allow for clear vision and efficient light transmission. Despite the advances, efficient and low cost solutions to clean antireflective surfaces have remained elusive. Here, we present a practical approach that enables the production of antireflective polymer surfaces based on moth-eye inspired features incorporating photoinduced self-cleaning properties and enhanced mechanical resistance. The methodology involves the fabrication of sub-wavelength moth-eye nanofeatures onto transparent surface composite films in a combined processing step of nanoparticle coating and surface nanoimprinting. The resulting surfaces reduced the optical reflection losses from values of 9% of typical PMMA plastic films to an optimum value of 0.6% in the case of double-sided moth-eye nanoimprinted films. The composite moth-eye topography also showed an improved stiffness and scratch resistance. This technology represents a significant advancement not limited by scale, for the development of antireflective films for low cost application products.

The layered rare-earth diantimonides RSb 2 are anisotropic metals with generally low electronic densities whose properties can be modified by substituting the rare earth. LaSb 2 is a nonmagnetic metal with a low residual resistivity presenting a low-temperature magnetoresistance that does not saturate with the magnetic field. It has been proposed that the latter can be associated to a charge density wave (CDW), but no CDW has yet been found. Here we find a kink in the resistivity above room temperature in LaSb 2 (at 355 K) and show that the kink becomes much more pronounced with substitution of La by Ce along the La 1−x Ce x Sb 2 series. We find signatures of a CDW in x-ray scattering, specific heat, and scanning tunneling microscopy (STM) experiments in particular for x ≈ 0.5. We observe a distortion of rare-earth-Sb bonds lying in-plane of the tetragonal crystal using x-ray scattering, an anomaly in the specific heat at the same temperature as the kink in resistivity and charge modulations in STM. We conclude that LaSb 2 has a CDW which is stabilized in the La 1−x Ce x Sb 2 series due to substitutional disorder.