But now, an exciting new upstart is challenging graphene's title. Meet goldene, a two-dimensional sheet of gold that has its own strange properties.

It wasn't long ago that graphene was constantly hogging the headlines, thanks to it being incredibly strong, thin, flexible, lightweight, and an excellent conductor of heat and electricity. And all this from some very humble beginnings – this 'wonder material' was first created by using some sticky tape to peel one-atom-thick layers off a chunk of graphite.