The field of “spintronics”
has the potential to deliver electronic devices that are both faster and
consume less power than the current
devices. To realize this potential materials where the spins of the mobile
electrons are spin polarized are needed.
The double perovskite Sr2CrReO6 is one such promising
material. Theoretical studies predict
that at room temperature it should be a metal where 85−100% of the mobile
electrons have parallel spins. However,
experimental studies of Sr2CrReO6 have been hampered by the
inability of researchers to keep Cr and Re atoms from occasionally switching
places in the crystal. These “mistakes”
called antisite defects negatively impact the magnetic and electrical
properties. Researchers at The Ohio State University have for the first time
succeeded in preparing high quality epitaxial films of Sr2CrReO6
where the Cr and Re atoms are nearly perfectly ordered. Measurements made on these films shed new
light on the properties of this material. The effect of spin-orbit coupling, a
property associated with compounds containing heavy elements (in this case Re),
is evident in the magnetic properties.
More surprising is the observation
that the material is a semiconductor rather than a metal, something that had
not been anticipated. Not only is the
ability to grow highly ordered double perovskite films a technological
breakthrough, the unexpected semiconducting behavior is likely to stimulate new
studies to understand the intriguing properties of Sr2CrReO6.
