<div class="articleText" style="display: inline;"> <p>A peek into the inner workings of high temperature superconductors has been provided by new work by an international collaboration reporting in <i>Nature</i>. A fuller understanding of the transition to superconducting could open new research lines into room temperature superconductors—leading to lossless power transmission and a host of other applications.</p> <p>The new research comes from a team comprised of researchers at the University of Cambridge in the UK, the National High Magnetic Field Laboratories at Los Alamos National Laboratory and Florida State University in the US, and the University of British Columbia and the Canadian Institute for Advanced Research in Canada.</p> <p>The team focused their efforts on samples of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6.51</sub>. Copper oxides such as this behave as insulating magnets before doping, but on the addition of charge carriers become high-temperature superconductors as the carriers pair up. The microscopic physics of that transition, however, has remained a mystery.</p> <p>While superconductors are difficult to investigate using common techniques, the application of high external magnetic fields creates ‘vortices’—regions where the superconductivity is destroyed but whose electronic structure can be studied. To investigate that, the team studied the oscillations of the magnetization of the samples in the presence of an externally applied magnetic field. Such oscillations occur as a result of the de Haas-van Alphen effect, a quantum mechanical phenomenon that arises due to the quantization of electron energies.</p> <p>Prior experimental results have shown a prominent oscillation that occurs at around 500 T, suggesting a small ‘pocket’ in the Fermi surface for carriers. The new work, however, demonstrates an oscillation at 1 650 T, some 30 times weaker but corresponding to more than three times as many charge carriers, each with twice the effective particle mass as the 500 T pocket [Sebastian <i>et. al., Nature</i> (2008) <strong>454</strong>, 200].</p> <p>“We have been able to shed light on the location in the electronic structure where ‘pockets’ of doped carriers gather,” said lead author Suchitra E. Sebastian of the University of Cambridge—a crucial step toward understanding how the carriers pair up for superconducting.</p> <p>As with many findings in superconductivity research, however, the results have raised many questions, in particular about the implied interplay between magnetism and superconductivity. The two may be separate, competing effects, so that in regions of the material where superconductive behavior is quenched, magnetism takes over. Alternatively, the non-superconducting vortices might work together to create a macroscopic magnetization while the remainder of the structure superconducts.</p> </div>