Spin-caloritronics is a new research field combining Spintronics (spin transport electronics) and Thermoelectricity (heat transport electronics) in magnetic nanostructured systems. At such a scale, thermal gradients can play an active role to control and manipulate spin-based effects enabling the generation of thermally induced spin currents or even thermally driven magnetization reversal.
- We investigate thermovoltages in the nanometer-thin films of the MTJ,
- use thermovoltage measurements as an methode to probe the temperature behavior,
- and quantifies how thermal currents excite oscillation via the thermal STT in vortex oscillators.
This approach is based on recently observed large tunneling magneto Seebeck ratios in magnetic tunnel junction (MTJ) structures, suggesting the potentiality of such devices, not only for magnetic random access memory (MRAM) devices or Spin Transfer Torque Nano-oscillators (STNOs), but also for on-chip energy harvesting applications. On the other hand, we believe that the exploration of heat driven magnetization dynamics could enable a better comprehension of Spin Transfer Torque (STT) magnetization dynamic phenomena in MTJ nanodevices and the contribution of heat, charge and spin currents at such conditions.
JRP SpinCal project partners Physikalisch-Technischen Bundesanstalt (PTB), Germany; National Physical Laboratory (NPL), UK; Istituto Nazionale di Recerca Metrologica (INRIM), Italy; University of Bielefeld, Germany; Cambridge University, UK;International Iberian Nanotechnology Laboratory (INL), Portugal; Institute of Physics of Czech Republic (FZU), Czech Republic.
An wafer full of Nernst effect thermometers. The heat flow perpendicular to the surface creates an Nernst voltage in the metallic thin films.
These are the thermovoltage results of the first generation of MTJ devices. These result where published in the work of Liebing et al. and started the spin-caloritronic research at INL.
Device structure with highlighted elements (top contact, bottom contact, heaterline, and MTJ) and a sketch of the measurement setup: a Joule heating current is applied through the heaterline and the thermovoltage is measured between the top contact and the bottom contact of the device structure. More details at Böhnert et al...
A sketch of the different thermal behavior depending on the thermal conductivity of the alumina and the tunnel barrier. More details at Böhnert et al..
2018 Conference on Precision Electromagnetic Measurements, IEEE, 2018.
Physics Letters A, 2018, ISSN: 0375-9601.
Journal of Physics: Condensed Matter, 29 (18), pp. 185303, 2017.
2017 IEEE International Magnetics Conference (INTERMAG), pp. 1-1, 2017.
Physical Review B, 95 , pp. 104441, 2017.
Applied Physics Letters, 110 (23), pp. 232403, 2017.
Applied Physics Letters, 102 (24), pp. 242413, 2013.