The polarized photoluminescence emitted on the edge of a series of aluminum‐rich (Al,Ga)N‐AlN quantum wells (QWs) grown by molecular beam epitaxy on AlN templates deposited by metal organic chemical vapor deposition on c‐plane sapphire is measured. The contrast and the principal axis of the emission diagrams for 2 nm‐thick (Al,Ga)N QWs grown for aluminum compositions between 40% and 90% are studied. The light is emitted on the edge of the QWs at wavelengths going from 280 nm down to 209 nm. The emission diagram, a change from oblate to prolate with respect to the in‐plane orientation, for an aluminum composition is found to occur around 72%, that is, at an emission wavelength of about 235 nm. The orientations and shapes of the edge‐emission diagrams indicate that the fluctuations of the composition of the (Al,Ga)N confining layer are deep enough for producing intravalence band mixings. This property, that acts in concert with the built‐in strain and quantum‐confined Stark effect, contributes to the anisotropy of the light emission when the aluminum composition reaches 60–70%, that is, for an emission wavelength of 260–235 nm.

Abstract In a 2D electron system (2DES) the breaking of the inversion, time‐reversal and bulk crystal‐field symmetries is interlaced with the effects of spin‐orbit coupling (SOC) triggering exotic quantum phenomena. Here, epitaxial engineering is used to design and realize a 2DES characterized simultaneously by ferromagnetic order, large Rashba SOC and hexagonal band warping at the (111) interfaces between LaAlO 3 , EuTiO 3 , and SrTiO 3 insulators. The 2DES displays anomalous quantum corrections to the magneto‐conductance driven by the time‐reversal‐symmetry breaking occurring below the magnetic transition temperature. The results are explained by the emergence of a non‐trivial Berry phase and competing weak anti‐localization/weak localization back‐scattering of Dirac‐like fermions, mimicking the phenomenology of gapped topological insulators. These findings open perspectives for the engineering of novel spin‐polarized functional 2DES holding promises in spin‐orbitronics and topological electronics.

We address the question of how viscosity impacts the growth of gravitation waves, such as those on the ocean, when they are driven by wind. There is so far no general rigorous theory for this energy transfer. We extend Miles' approach [J. W. Miles, “On the generation of surface waves by shear flows,” J. Fluid Mech. 3, 185–204 (1957)], using the same logarithmic wind profile, to incorporate bulk viscosity and derive modified growth rates. Exploiting the fact that water waves fall into the “weak viscosity” regime, we produce analytical expressions for the growth rate, which we solve using the numerical method proposed by Beji and Nadaoka [“Solution of Rayleigh's instability equation for arbitrary wind profiles,” J. Fluid Mech. 500, 65–73 (2004)]. Our results confirm that corrections to the growth rates are significant for wavelengths below a meter, and for weak to modest wind strengths. We show that all wave growth is suppressed, due to viscous effects, below a critical wind strength. We also show that the wave age corresponding to a developed sea is reduced by viscosity. We quantitatively characterize the zones, in terms of wind strength and wavelength, for which the wave growth is suppressed by viscosity.