Thermal Spin-Transfer Torques

• Applicants: Alina Deac, Ph.D.; Privatdozent Dr. Jürgen Lindner
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 257853858

Spincaloritronics, a recent research area which aims at investigating new phenomena that can enable inherently generated Joule heating to be functionalized in microelectronic circuit design, has the potential to bring about a whole new generation of Green Information-Communication Technology (ICT) devices. To-date, it has been theoretically predicted and experimentally demonstrated that temperature gradients can induce spin-currents and spin-accumulation in ferromagnets (known as the spin-Seebeck effect), tunneling between two magnetic layers separated by an insulator (magneto-Seebeck effect), spin-injection from a ferromagnet to a semiconductor (spin Seebeck tunneling) and so on. It has also been theoretically predicted that spin currents generated by temperature gradients in MgO-based magnetic tunnel junctions can induce spin-transfer torques large enough to cause switching. Nevertheless, experimental evidence remains elusive to-date, possibly because disorder at the interfaces between the MgO barrier considerably reduces the magnitude of the thermal torques and/or the temperature gradients which can be experimentally achieved are not sufficiently high. Here, we propose a resonant, open-circuit approach which will enable us to provide proof-of-concept for the existence of thermal spin-transfer torques even if their magnitude is considerably lower than expected. In addition, it will allow us to determine the angular dependence of both the in-plane and perpendicular spin-torque terms, thus providing a concrete test-bench for theoretical models.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1538: Spin Caloric Transport (SpinCaT)