Anisotropic Pauli spin blockade in hole quantum dots
  We present measurements on gate-defined double quantum dots in Ge-Si core-shell nanowires, which we tune to a regime with visible shell filling in both dots. We observe a Pauli spin blockade and can assign the measured leakage current at low magnetic fields to spin-flip cotunneling, for which we measure a strong anisotropy related to an anisotropic g-factor. At higher magnetic fields we see signatures for leakage current caused by spin-orbit coupling between (1,1)-singlet and (2,0)-triplet states. Taking into account these anisotropic spin-flip mechanisms, we can choose the magnetic field direction with the longest spin lifetime for improved spin-orbit qubits. 
Matthias Brauns, Joost Ridderbos, Ang Li, Erik P.A.M. Bakkers, Wilfred   G. van der Wiel, Floris A. Zwanenburg
cond-mat.mes-hall quant-ph