Good old sputtering might be a route to MRAM
- Autore:Ella Cai
- Rilasciare il:2018-08-24
The University of Minnesota has sputtered a ‘topological insulator’ – a solid that conducts on its surface but not inside – avoiding the single crystal growth process or molecular beam epitaxy normally needed.
Bismuth selenide (Bi2Se3) is the material, magnetron-sputtered into a thin film of particles <6nm across in hetero-structures with CoFeB –
“Using the sputtering process to fabricate a quantum material like a bismuth-selenide-based topological insulator is against the intuitive instincts of all researchers in the field and actually is not supported by any existing theory,” said engineering professor Jian-Ping Wang.
As grain size was decreased, quantum confinement emerged – where electrons in the material act differently than in bulk, giving additional control over the electron behaviour.
Such materials could exploit spin–orbit torque to create fast low-power memory.
In this case, the material BixSe(1–x)/Co20Fe60B20 delivered a spin torque efficiency of over 18, “moreover, switching of the perpendicular CoFeB multilayers using the spin-orbital torque from the BixSe(1–x) was observed at room temperature with a low critical magnetisation switching current density of 4.3×105A/cm2,” said the team in the abstract of ‘Room-temperature high spin–orbit torque due to quantum confinement in sputtered BixSe(1–x) films‘, published in Nature Materials.
“We used a quantum material that has attracted a lot of attention by the semiconductor industry in the past few years, but created it in unique way that resulted in a material with new physical and spin-electronic properties that could greatly improve computing and memory efficiency,” said Wang.
The University of Minnesota worked with Semiconductor Research Corporation and the US Defense Advanced Research Projects Agency.
Bismuth selenide (Bi2Se3) is the material, magnetron-sputtered into a thin film of particles <6nm across in hetero-structures with CoFeB –
“Using the sputtering process to fabricate a quantum material like a bismuth-selenide-based topological insulator is against the intuitive instincts of all researchers in the field and actually is not supported by any existing theory,” said engineering professor Jian-Ping Wang.
As grain size was decreased, quantum confinement emerged – where electrons in the material act differently than in bulk, giving additional control over the electron behaviour.
Such materials could exploit spin–orbit torque to create fast low-power memory.
In this case, the material BixSe(1–x)/Co20Fe60B20 delivered a spin torque efficiency of over 18, “moreover, switching of the perpendicular CoFeB multilayers using the spin-orbital torque from the BixSe(1–x) was observed at room temperature with a low critical magnetisation switching current density of 4.3×105A/cm2,” said the team in the abstract of ‘Room-temperature high spin–orbit torque due to quantum confinement in sputtered BixSe(1–x) films‘, published in Nature Materials.
“We used a quantum material that has attracted a lot of attention by the semiconductor industry in the past few years, but created it in unique way that resulted in a material with new physical and spin-electronic properties that could greatly improve computing and memory efficiency,” said Wang.
The University of Minnesota worked with Semiconductor Research Corporation and the US Defense Advanced Research Projects Agency.
