Spin transfer torques

This tutorial article introduces the physics of spin transfer torques in magnetic devices. Our intention is that it be accessible to beginning graduate students. We provide an elementary discussion of the mechanism of spin transfer torque and review the theoretical and experimental progress in this field. This article is meant to set the stage for the articles which follow in this volume of the Journal of Magnetism and Magnetic Materials, which focus in more depth on particularly interesting aspects of spin-torque physics and highlight unanswered questions that might be productive topics for future research.