Scientists have laid the foundations for a high-performance 'molecular fridge' capable of reaching temperatures within a few thousandths of a degree of absolute zero (0K) with a high degree of efficiency. Such ultracoolers could have applications in areas such as ultra-low temperature physics, where alternative technologies such as those that rely on expensive and rare helium-3 could be unsuitable or too costly.The system relies on a phenomenon called the magneto-caloric effect, where the removal of a magnetic field from a ferromagnetic material causes a drop in temperature. The key to achieving a high magneto-caloric effect is to have a material...