Today almost all information stored on hard disc drives or cloud servers is recorded in magnetic media, because it is non-volatile (i.e. it retains the information when power is switched off) and cheap. For portable devices such as mobile phones and tablets, other forms of non-magnetic memory are used because the technology based on magnetism is impractical and is not energy efficient. In an age of mass data storage and portable devices which collect and process information, the search is on to find smaller, faster, cheaper and more energy efficient ways, of both processing and storing increasing amounts of data.