Strong friction anisotropy is found when the twofold surface of an atomically clean aluminum-nickel-cobalt quasicrystal slides against a thiol-passivated titanium-nitride tip. Friction along the aperiodic direction is one-eighth as much as that along the periodic direction. This anisotropy, which is about three times as large as the highest value observed in anisotropic crystalline surfaces, disappears after the surface is oxidized in air. These results reveal a strong connection between interface atomic structure and the mechanisms by which energy is dissipated, which likely include electronic or phononic contributions, or both.

Samples of aligned ${\mathrm{MgB}}_2$ crystallites have been prepared, allowing for the first time the direct identification of an upper critical field anisotropy $H_{c2\mathrm{}}^{\mathrm{ab}}{/H}_{c2\mathrm{}}^c={\xi }_{\mathrm{ab}}/{\xi }_c\simeq 1.7$, with ${\xi }_{o,ab}\simeq 70Å$, ${\xi }_{o,c}\simeq 40Å$, and a mass anisotropy ratio $m_{\mathrm{ab}}{/m}_c\simeq 0.3$. A ferromagnetic background signal was identified, possibly related to the raw materials purity.

Magic-angle twisted bilayer graphene has emerged as a powerful platform for studying strongly correlated electron physics, owing to its almost dispersionless low-energy bands and the ability to tune the band filling by electrostatic gating. Techniques to control the twist angle between graphene layers have led to rapid experimental progress but improving sample quality is essential for separating the delicate correlated electron physics from disorder effects. Owing to the 2D nature of the system and the relatively low carrier density, the samples are highly susceptible to small doping inhomogeneity which can drastically modify the local potential landscape. This potential disorder is distinct from the twist angle variation which has been studied elsewhere. Here, by using low temperature scanning tunneling spectroscopy and planar tunneling junction measurements, we demonstrate that flat bands in twisted bilayer graphene can amplify small doping inhomogeneity that surprisingly leads to carrier confinement, which in graphene could previously only be realized in the presence of a strong magnetic field.