We saw mobilephones and notebooks upgraded fast every year; we read a lot about the green electric cars and wind turbines for renewable energy and reduced pollution. But we seldom know that a key challenge for all those technology is the super-powerful magnets. Governments are funding research projects in making cheaper but stronger magnetic materials. Scientists try to combine nanoparticles of rare-earth magnets with nanoparticles of cheaper magnetic materials, to create super-strong end-products with far less of the expensive ingredients, rare earth elements. "The grains in a successful nanocomposite must be small (10 nanometres or less); have the right crystal structure; have aligned magnetic directions; and be tightly packed.