Cover Picture: Competing energy scales in high‐temperature superconductors: Ultrafast pump–probe studies (Phys. Status Solidi RRL 1/2011)

The cover picture of this issue is related to the Review@RRL article by Elbert E. M. Chia et al. (pp. 1–9). The figure depicts the phase diagram of high-temperature superconductors, where the antiferromagnetic phase, pseudogap phase, and the superconducting phase emerge, and sometimes even coexist or compete with one another, at different hole dopings. When a pump pulse arrives at a sample from the top, the pump photon breaks Cooper pairs and creates quasiparticles. A probe pulse that arrives shortly after tracks the time evolution of the quasiparticle population. The curves of blue and red circles depict the pump–probe signal of the cuprate superconductor Tl-2223 below the Néel temperature TN. The signal has two opposite components, showing the coexistence of superconductivity and antiferromagnetism at low temperatures.