By Hamish Johnston

In 1911 the Dutch physicists Heike Kamerlingh Onnes and Gilles Holst discovered superconductivity in mercury.

One hundred years later, physicists are still hard at work studying a growing number of superconducting materials.

Now you can celebrate the centenary by enjoying a free download of the April 2011 issue of Physics World, which is packed full of articles on superconductors.

The issue contains a handy wallchart showing the inexorable rise in critical temperature as more superconductors were discovered. The chart also highlights the six Nobel prizes associated with superconductors and other important events in the field.

Relive the key events of the last 100 years in the company of Paul Michael Grant, who also presents his top five applications of superconductivity with the biggest impact on society today.

Stephen Blundell examines the pivotal role in understanding these materials played by the brothers Fritz and Heinz London, while Ted Forgan recalls the euphoric early days of high-temperature superconductivity 25 years ago, and Laura Greene calls for a global collaboration to reveal the next generation of high-temperature materials.

Finally, don’t miss our profiles of three key industrial players – GE, American Superconductor and Oxford Instruments – as well as our fabulous superconductivity timeline.

You can download the special issue here.