Commentary:  The first experimental observations of current noise in organic bulk-heterojunction solar cells are reported and analysed. The noise spectrum has a usual 1/f^a form at low frequencies. At frequencies of ~ 8-10kHz, a broad maximum shows up. This intriguing feature is a direct evidence of hidden cyclostationary processes in the system. The maximum depends strongly on the background intensity, the extent of degradation and temperature. A kinetic Monte Carlo (KMC) simulation of charge transport in a disordered system has been carried out to understand the results. The inclusion of a transport level or a mobility edge is the new feature of simulations. The flicker noise is well reproduced, and the maximum is argued to arise from space-charge effects.

Commentary: YFe_1-xCr_xO₃  is an unusual system. It is a solid solution of the Yttrium orthoferrite and orthochromite materials. The end points (YFeO₃ and YCrO₃) are boring canted anti-ferromagnets with a monotonic temperature dependent magnetization. The alloy, however, shows rich and unexpected behaviour such as magnetization reversal and compensation point(s). It turns out that the origin of such surprising behaviour is a three-way Dzyaloshinskii-Moriya interaction between Fe-Fe, Cr-Cr and Fe-Cr. Given that the first two are in the same direction, but the third is opposite, the whole range of experimental behaviour can be accounted for, in a quantitative way, using a simple minimalist theoretical approach. Read on.