Nanomaterial demonstrates unusual magnetic property

Science : Coercivity is a measure of how difficult it is to change the magnetic orientation of the atoms in a material. For most materials, coercivity changes gradually depending on temperature, but a new nanomaterial exhibits rapid coercivity changes over a small range of temperatures. Ivan Schuller, of the University of California, San Diego, and his colleagues created the material by coating a 100-nm wafer of vanadium oxide with 10 nm of nickle. They then placed the wafer in a magnetic field and cooled it to −153 °C. Between −88 and −108 °C, the coercivity of the material increased significantly, but at −123 °C, it quickly dropped to half its maximum. Schuller’s team believes that the change is due to vanadium oxide having two different atomic arrangements—one above −88 °C and another below −123 °C. Between those temperatures the material’s structure is a mixture of the two arrangements, which makes it harder for the magnetic orientation in the surrounding nickle to switch en masse. If a similar material can be created at room temperatures, it could be useful for magnetic data storage devices such as computer hard drives.