Scientists at the University of York, in partnership with researchers from Tohuku University in Japan, have revealed how defects affect the atomic structure of magnetite and say this discovery may enable the development of more powerful electronic devices. Magnetite has a number of applications, including spintronics, where it can be used to help develop more efficient and higher capacity memories.
Electrical currents in magnetite should be carried by electrons which all have the same spin state. However, it fails to demonstrate the characteristics expected and this is thought to be due to defects in its atomic structure.
Now, the researchers have resolved the atomic scale structure of two dimensional antiphase boundary defects (APBs) in the material. The team used theoretical modelling to predict the structure of the defects through a series of first principles calculations based on quantum mechanics, then confirmed it experimentally using high resolution transmission electron microscopy. The results showed that APB defects are unusually stable and cause antiferromagnetic coupling, leading to reduced spin polarisation.
Dr Keith McKenna, an EPSRC Fellow who led the team at York, said: "Our study has predicted what the atomic structure of the defects should be and then it confirmed it using electron microscopy. The spins on either side of these defects point in opposite directions creating areas that are not 100% spin polarised.
"We can now have confidence in making predictions about magnetite's electronic and magnetic properties which will help optimisation of the material. This will help the development of smaller more powerful electronic devices, particularly more efficient memory devices."
Author
Graham Pitcher
Source: www.newelectronics.co.uk