Number Parity effect in the normal state of SrTiO3
Abstract
We study the recently discovered even-odd effects in the normal state of single-electron devices manufactured at strontium titanium oxide/lanthanum aluminum oxide interfaces (STO/LAO). Within the framework of the number parity-projected formalism and a phenomenological fermion-boson model we find that, in sharp contrast to conventional superconductors, the crossover temperature T* for the onset of number parity effect is considerably larger than the superconducting transition temperature Tc due to the existence of a pairing gap above Tc. Furthermore, the finite lifetime of the preformed pairs reduces by several orders of magnitude the effective number of states N eff available for the unpaired quasiparticle in the odd parity state of the Coulomb blockaded STO/LAO island. Our findings are in qualitative agreement with the experimental results reported by Levy and coworkers for STO/LAO based single electron devices.