  Understanding quantitatively the heating dynamics in magnetic tunnel
junctions (MTJ) submitted to current pulses is very important in the context of
spin-transfer-torque magnetic random access memory development. Here we provide
a method to probe the heating of MTJ using the RKKY coupling of a synthetic
ferrimagnetic storage layer as a thermal sensor. The temperature increase
versus applied bias voltage is measured thanks to the decrease of the spin-flop
field with temperature. This method allows distinguishing spin transfer torque
(STT) effects from the influence of temperature on the switching field. The
heating dynamics is then studied in real-time by probing the conductance
variation due to spin-flop rotation during heating. This approach provides a
new method for measuring fast heating in spintronic devices, particularly
magnetic random access memory (MRAM) using thermally assisted or spin transfer
torque writing.
