A super-elastic collision is one that results in an increase of kinetic energy in the colliding system. A probable occurrence of this type of collision is shown in the huge, magnetized plasmas of two coronal mass ejections from the Sun. Article p923 COVER IMAGE: NASA/NRL/RAL COVER DESIGN: ALLEN BEATTIE

Sudden bursts of charged particles emitted from the surface of the Sun can disrupt the satellites orbiting Earth. However, the mechanisms that drive these so-called coronal mass ejections remain unclear. An advanced computer model now establishes a link between the onset of an ejection and the emergence of magnetic flux into the solar atmosphere. Article p845; News & Views p783 COVER IMAGE: COOPER DOWNS AND ILIA IANKOV ROUSSEV COVER DESIGN: ALLEN BEATTIE

Chirality is usually manifested by differences in a material's response to left- and right-circularly polarized light. This difference is the result of the specific distribution of charge within chiral materials. A similar response has now been found to result from the chiral spin structure of an antiferromagnet. Letter p734 COVER IMAGE: DAVID SZALLER AND ISTVAN KéZSMáRKI COVER DESIGN: ALLEN BEATTIE

Magnetic vortices confined to thin films gyrate with dynamics that are determined by the vortex-core polarity, which switches when the gyration is fast enough. Fine-tuning these core-reversal oscillations reveals rich nonlinear behaviour, including commensurate and chaotic states. Article p682 COVER IMAGE: JOO-VON KIM AND ANTONIO RUOTOLO COVER DESIGN: ALLEN BEATTIE

An ideal amplifier has low noise, operates over a broad frequency range and has large dynamic range. A superconducting-resonator-based amplifier that combines all of these qualities is now demonstrated. The concept is applicable throughout the microwave, millimetre-wave and submillimetre-wave bands and can achieve a noise limit very close to that set by quantum mechanics. Letter p623 COVER IMAGE: PHOTOGRAPHY BY PETER DAY; ARTWORK BY CMG DESIGN COVER DESIGN: ALLEN BEATTIE

The penetration of a superconducting current from a superconductor into a half-metallic ferromagnet is usually forbidden. Resonances in the conductance spectra of superconductor/half-metal heterostructures suggests this restriction is lifted by the occurrence of unconventional equal-spin Andreev reflection. Letter p539 IMAGE: JAVIER E. VILLEGAS AND C. VISANI COVER DESIGN: ALLEN BEATTIE

The proximity effect enables the injection of Cooper pairs from a superconductor into a normal metal, but they usually don't travel far into the metal. A study of the propagation of Cooper pairs from irregularly shaped superconducting islands on a metal film reveals that the pairs can travel further than expected for certain island geometries. Letter p464 IMAGE: JUNGDAE KIM, GREG FIETE AND CHIH-KANG SHIHCOVER DESIGN: ALLEN BEATTIE

A demonstration of the ability to coherently control the collective attosecond dynamics of relativistic electrons driven through a plasma by an intense laser represents an important step in the development of techniques to manipulate and study extreme states of matter. Article p416 IMAGE: ARNAUD MALVACHE AND STéPHANE HEUET COVER DESIGN: ALLEN BEATTIE

Rapid particle acceleration is possible using a fixed-field alternating-gradient machine — but 'scaling' in its design has been necessary to avoid beam blow-up and loss. The demonstration now of acceleration in such a machine without scaling has positive implications for future particle accelerators. Article p243 COVER IMAGE: ANDREW COLLINS COVER DESIGN: ALLEN BEATTIE

The cover image of the March 2012 issue of Nature Physics should have been credited to Andrew Collins. Corrected in the HTML and PDF versions after print, 12 March 2012.

Chiral superconducting states are expected to support a variety of exotic and potentially useful phenomena. Theoretical analysis suggests that just such a state could emerge in a doped graphene monolayer. Article p158; News & Views p111 COVER IMAGE: ANDREY CHUBUKOV, RAHUL NANDKISHORE AND LEONID LEVITOV COVER DESIGN: ALLEN BEATTIE

Laser-driven proton accelerators could enable more effective cancer treatment. But to fulfil this function, proton beams with a higher energy and narrower energy spread will need to be produced. Discovery of a laser-plasma acceleration mechanism that generates 20 MeV proton beams with a 1% spread is a promising step. Article p95 COVER IMAGE: CHAN JOSHI, FREDERICO FIUZA AND RICARDO FONSECA COVER DESIGN: KAREN MOORE