0.7 Analogue structures and exchange interactions in quantum wires

We present experimental studies of crossings of spin-split one-dimensional subbands in ballistic quantum wires in an in-plane magnetic field B∥. At low electron densities, a spontaneous spin-splitting occurs as subbands cross, which gives rise to additional non-quantised conductance structures called 0.7 analogues. We analyse the data within a spin-density-functional model, which includes exchange interactions in a magnetic field. Focussing on the region of the crossings of spin-split subbands, it is found that the energy levels rearrange as they cross due to exchange interactions.