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Peltier, Seebeck, and Nernst Effects in Ferromagnetic Metals with In-Plane Thermal Gradients

Event Details

Event Dates: 

Thursday, November 21, 2013 - 12:00pm

Seminar Location: 

  • Duane Physics Room D142

Speaker Name(s): 

Barry Zink

Speaker Affiliation(s): 

University of Denver
Seminar Type/Subject

Scientific Seminar Type: 

  • Condensed Matter Seminar

Event Details & Abstract: 

The reliable generation of pure spin currents is an important ingredient in future spintronic circuits that may offer lower power consumption and greater processing capabilities than current technology. Recently the concept that a thermal gradient applied to a ferromagnet could produce a pure spin current, a phenomenon called the spin Seebeck effect (SSE), has generated a great deal of excitement and effort in the spintronics community.  This is one aspect of a growing field some call spincaloritronics, the interaction of heat, charge and spin currents in ferromagnetic (FM) systems.  As interest in this field grows, the physics of thermoelectric effects in ferromagnets becomes more critical.   Potential optimization and application of spincaloritronic phenomena, such as the SSE, is possible only if the fundamental interactions are understood.   Reliable measurements of thermoelectric effects in thin films and nanostructures require accurate generation and control of the thermal gradient applied to systems with tiny thermal mass.  This talk will present recent measurements of Peltier, Seebeck, and Nernst effects in thin film FM metals, made using unique micromachined thermal isolation platforms.  These allow "zero substrate" heating of thin films and have led to important recent results including: [1] the observation of the planar Nernst effect (PNE) and elimination of the SSE when an in-plane thermal gradient is applied to FM metals, [2] the direct linkage of the PNE to AMR, magnetothermopower and spin-dependent scattering in FM metals, and [3] the first measurements of the Peltier coefficient in FM metal thin films and proof of Onsager reciprocity between Peltier and Seebeck currents even in the presence of phonon-magnon drag.

 

[1]  A. D. Avery, M. R. Pufall, B. L. Zink, PRL 109, 196602 (2012)

[2] A. D. Avery, M. R. Pufall, B. L. Zink,  PRB 86, 184408 (2012).

[3] A. D. Avery and B. L. Zink, PRL 111, 126602 (2013).