Thermally Assisted Magnetization Switching on Magnetic Tunnel Junctions With Perpendicularly Magnetized TbFe Layer

Abstract

Perpendicular magnetized tunnel junctions (MTJs), whose stack is [Co/Pd] / MgO / TbFe, were fabricated since the TbFe memory layer has a large perpendicular anisotropy and a low Curie temperature, which are suitable for thermally assisted (TA) switching. The TA switching of the TbFe layer due to a Joule heating created by a pulse current through the tunnel junction was confirmed. The MTJ with MgO 1.4 nm layer exhibited the MR ratio of 9 %, and the resistance area product RA of 342 Ωμm2 at low bias voltage of 40 mV. The coercivity of TbFe at room temperature was about 1.5 kOe, while the magnetic switching at low magnetic field of 100 Oe was confirmed by the application of a current pulse with duration of 100 msec through the tunnel junction which creates the Joule heating. Moreover, the dependence of the power density necessary to switch the TbFe layer on the external applied field was measured. The required power density to complete the TA switching decreased linearly with the increase of the applied field and the TA switching of TbFe at low external field of 100 Oe was confirmed at the applied power density of 2.2 mW/μm2.