Spin blockade and lifetime-enhanced transport in a few-electron Si/SiGe double quantum dot

Spin blockade occurs when an electron is unable to access an energetically favourable path through a quantum dot owing to spin conservation, resulting in a blockade of the current through the dot(1-6). Spin blockade is the basis of a number of recent advances in spintronics, including the measurement and the manipulation of individual electron spins(7,8). We report measurements of the spin blockade regime in a silicon double quantum dot, revealing a complementary phenomenon: lifetime-enhanced transport. We argue that our observations arise because the decay times for electron spins in silicon are long, enabling the electron to maintain its spin throughout its transit across the quantum dot and access fast paths that exist in some spin channels but not in others. Such long spin lifetimes are important for applications such as quantum computation and, more generally, spintronics.