Materials for Room Temperature Spintronics @ Ohio State University

Author(s):

Adam Hauser, Manisha Dixit, Robert Williams, Hamish Fraser, Fengyuan Yang (Ohio State University)

Ordered double perovskites, such as Sr₂FeMoO₆, are among the very few materials that allow electrons of one spin direction to move through them as though they were passing through a normal metal, while blocking electrons of the opposite spin.  Materials that behave this way at room temperature are even more exotic.

To unlock the potential of Sr2FeMoO6 it is essential to deposit films where the iron (Fe) and molybdenum (Mo) ions are highly ordered and the formation of unwanted phases is suppressed. CEM researchers have been able to deposit highly ordered, single crystalline films of Sr₂FeMoO₆ that retain their magnetism to temperatures over 227°C.

Films were grown by sputtering in an ultrapure Ar atmosphere.  X-ray diffraction measurements show that films are epitaxial and phase pure.  X-ray diffraction measurements of films grown on 111 SrTiO₃ substrates allow us to estimate that 93% of the Fe & Mo atoms reside on the correct sites, confirming the high degree of order suggested by the TEM images.  Films deposited using a novel growth geometry have exciting magnetic properties:

• Unique magnetic shape anisotropy
• Stoichiometric Fe to Mo ratio
• Saturation magnetization up to 4 mB/f.u. at T = 5 K
• Curie temperature well above 500

More details on Center's website