13:45 〜 14:00
▼ [22p-W241-3] Dot size dependence of magnetization switching by spin-orbit torque in antiferromagnet/ferromagnet structures
キーワード：spintronics,antiferromagnet,spin-orbit torque
Spin-orbit torque (SOT) induced magnetization switching is expected to be a new scheme to switch magnetization in three-terminal spintronics devices. The main issue of the scheme is a necessity of external in-plane magnetic field application for bipolar switching. Recently, it was shown that antiferromagnetic materials can be used as both a source of SOT and exchange-bias in antiferromagnet/ferromagnet heterostructures, allowing for an external-field-free switching. Here, we study the field-free switching in Pt/PtMn/[Co/Ni]2.5/MgO dots with diameters from 60 nm to 1000 nm.
We successfully observe external-field-free magnetization switching in perpendicular easy axis devices with tPtMn = 6.8 and 7.6 nm and sizes down to 60 nm. As the size decreases, analogue-like behaviour transforms to the commonly-observed scheme with two magnetization states. The threshold size is between 300 and 500 nm for tPtMn = 6.8 nm and between 200 and 250 nm for tPtMn = 7.6 nm. The switching current density is roughly the same with that in our previous study on micrometer-sized devices (~ 1×1011 A/m2) and it gradually increases with the size reduction below the threshold size.
We successfully observe external-field-free magnetization switching in perpendicular easy axis devices with tPtMn = 6.8 and 7.6 nm and sizes down to 60 nm. As the size decreases, analogue-like behaviour transforms to the commonly-observed scheme with two magnetization states. The threshold size is between 300 and 500 nm for tPtMn = 6.8 nm and between 200 and 250 nm for tPtMn = 7.6 nm. The switching current density is roughly the same with that in our previous study on micrometer-sized devices (~ 1×1011 A/m2) and it gradually increases with the size reduction below the threshold size.