Nonequilibrium Spin Fluctuations in Nonmagnetic Single-Electron Transistors and Quantum Dots

It is shown that nonequilibrium spin fluctuations significantly influence electronic transport in a single-electron transistor, when the spin relaxation on the island is slow. To describe spin fluctuations, the “orthodox” tunneling theory is generalized by taking into account the electron spin. It is shown that the transition between consecutive charge states can occur via high-spin states, which significantly modifies the shape of Coulomb steps and gives rise to additional resonances at low temperatures.