Effects of Magnetization Dynamics on Thermal and Thermoelectric Transport in Ferromagnetic Thin Films

#dynamics #magnetization #materials #spinelectronics
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As spintronic devices continue to shrink toward nanoscale dimensions, often employing new materials with more complicated magnetic ordering, the role that heat plays in these systems becomes more important and interesting.  Thermal gradients in spintronics can be unintentional, such as those generated by the high current densities often required to generate spin orbit torques, or intentional, such as when studying materials with the spin Seebeck effect [1].  After briefly overviewing the physics behind these thermal gradients, this talk will focus mainly on the specific question of how heat flow and associated thermoelectric effects in a ferromagnetic metal can be altered when long-lived spin dynamics are present.  Using measurements of Co-Fe iron alloy thin films made with custom micromachined thermal isolation platforms, we will first demonstrate a unique magnetic-field direction dependence in the heat flow of alloys with exceptionally low magnetic damping [2].  Comparison to measured charge transport on the exact same samples confirms the presence of large non-electronic contributions to heat flow when the alloy composition is tuned to the low-damping regime. This is in stark contrast with more typical transition metal ferromagnets or their alloys such as permalloy, where heat flow matches the expectations from charge flow exceptionally well [3].  We will then demonstrate that this spin-dynamics induced heat flow also causes a contribution to the thermoelectric power, in a novel manifestation of magnon drag. [4]  If time allows, I will introduce other key recent results in thermal spintronics, including ongoing work on metallic ferrimagnets. This work was supported by the U.S. National Science Foundation (DMR-2004646, ECCS-2116991)

 

[1] B. L. Zink, JMMM v. 564, 170120 (2022)

[2] M. R. Natale, et al., PRM v. 5, L111401 (2021)

[3] A. D. Avery, et al., PRB v. 92, 214410 (2015)

[4] M. R. Natale, et al., PRM v. 8. 044402 (2024).


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  • 5 Allee Guinier
  • Nancy, Lorraine
  • France 54011
  • Building: Institut Jean Lamour
  • Room Number: 4-A014
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  • Starts 17 June 2025 10:00 PM UTC
  • Ends 15 July 2025 04:48 PM UTC
  • No Admission Charge