Regensburg 2016 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 18: Spincaloric Transport
(Joint session of MA and TT organized by MA)

TT 18.7: Talk

Monday, March 7, 2016, 16:45–17:00, H31

Influence of laser heating on switching fields in magnetic tunnel junctions — •Hangfu Yang, Niklas Liebing, Xiukun Hu, Sibylle Sievers, Mark Bieler, and Hans W. Schumacher — Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany

The field of spin caloritronics focuses on the interplay between heat, charge and spin currents in magnetic systems and gained a lot of interest due to new phenomena such as the tunnel magneto-Seebeck effect [1] and the thermal spin transfer torque [2]. Here, we study the influence of temperature and temperature gradients on magnetic switching of the free layer of CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs). Thermal gradients across the MTJs are generated locally by femtosecond laser pulses. The switching of the free layer is determined by magnetostatic measurements of the critical switching curve as a function of the laser power. We find that the entire critical curve shifts up to 4 mT along the easy axis at a laser power of 110 mW. We show that the shift in the critical curve is caused by an increase of the overall temperature due to heat accumulation rather than by a temperature gradient. Future studies will focus on reducing the stationary temperature increase, allowing for the generation of larger temperature gradients in our samples.

[1] N. Liebing et al., Phys. Rev. Lett. 107, 177201 (2011); M. Walter et al., Nature Mater. 10, 742-746 (2011).

[2] M. Hatami et al., Phys. Rev. Lett. 99, 066603 (2007); G.M. Choi et al., Nature Phys. 11, 576-581 (2015).