Effects of the spin-orbit interaction on electron tunneling in single ferromagnetic nanoparticles

Abstract

Recent technological innovations such as giant magnetoresistance and spin-transfer torque, along with a desire for researching the emergence of magnetism from a fundamental level, has led to much interest in understanding nanometer scale ferromagnets. In this dissertation, I use sequential electron tunneling to study the differential conductance spectra and magnetic properties of single cobalt and nickel particles below 5 nm in diameter, and observe a wealth of material-dependent effects. The spin-orbit interaction is a key mechanism in the observation of a variety of effects, including giant electron spin g-factors and shifts in the anisotropy energy of the magnetic particle upon the addition of a single electron. I show how such effects can lead to an effective magnetization blockade, which allows for the voltage control of magnetic hysteresis. I model the quantum mechanical system characteristics using master equations, and propose a new type of spin-transfer torque device that relies on the magnetization blockade effect.