On the Road with Spin-Current: Spin-Pumping and Spin-Transfer Torque

On the Road with Spin-Current: Spin-Pumping and Spin-Transfer Torque


  • Wayne Saslow, Texas A&M University, College Station
October 27, 2017 - 10:00am to 11:00am


In spin-pumping a ferromagnet is driven into resonance, causing a spin current that can cross into an adjacent normal material. The excitations for this system can be described using Fermi liquid theory. When collisions are included, irreversible thermodynamics applies to ordinary conductivity and resonance experiments, with magnetic variables the quantization axis M and the spin excitation density m, called the spin accumulation. Bulk irreversible thermodynamics gives new Onsager-related cross-relaxation processes (M<=>m). Surface irreversible thermodynamics gives the driving force for both spin-pumping and spin-transfer torque (spin current crossing an interface and then drives M) and relates them. We outline a spintronics application to provide low-loss transfer of magnetic information, using both phenomena. Unexpected complexity occurs even at the first stage, where ferromagnetic resonance provides the driving force for spin-pumping.

Sponsoring Organization 

Materials Science and Technology Division Materials Theory Group


  • Chemical and Materials Sciences Building
  • Building: 4100
  • Room: J-302

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