New Superconductor Found by Sprinkling Cu Atoms

Superconductors can carry a large amount of electrical current without producing any wasteful heat. Today, they are used to produce the magnetic field in medical resonance imaging (MRI) units; in the future, superconductors may help to stabilize the national power grid while reducing waste in transmission, and they may also lead to improved ship propulsion. With such promise, the search for new superconductors is an intense, worldwide activity. Recently, PCCM researchers found that adding copper atoms into a layered material, TiSe₂, produces superconductivity. The Cu atoms donate electrons which form the Cooper pairs essential to superconductivity when the temperature is below 4 K. This sprinkling with Cu atoms also destroys an unusual electronic state called the charge-density-wave, which competes with superconductivity. Although the critical temperature here (4 K) is much lower than that in the high-temperature (Tc) superconductors, the phase diagram, suggestive of competing states, resembles that of the high-Tc cuprates,so researching the competition in Cu_xTiSe₂ may help elucidate the high-Tc cuprate phase diagram.