About the cover
Heat cycles provide almost all of the energy that a modern civilization consumes. The thermoelectric cycle, a latecomer compared with steam and gases, generates electrical power through the Seebeck effect, whereby an electric voltage is generated when a conductor is placed in a temperature gradient. The 2008 discovery of the spin Seebeck effect (go.nature.com/dlvhz2) whereby a thermal gradient applied to a spin-polarized material leads to a spatially varying transverse spin current in an adjacent non-spin-polarized material — led to a new line of research in spintronics. In this issue of Nature, Jaworski et al. describe something similar but three orders of magnitude more powerful, 'giant spin Seebeck effect' in a material (indium antimonide, InSb) that is non-magnetic but that has strong spinorbit coupling and phononelectron drag. They propose a mechanism for this phenomenon that relies on spin polarization only, not on magnetic exchange. The results, say the authors, show that the spin Seebeck effect can be of a magnitude that may make spin-based thermal-energy converters a reality, and possibly competitive with existing technologies. Cover: IMAGE BY Scott Denison © Roberto C. Myers & Joseph P. Heremans.