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Self-organised fractional quantisation in a hole quantum wire

Hole transport in quantum wires formed by electrostatic confinement in strained germanium two-dimensional layers is investigated. The ballistic conductance characteristics show the regular staircase of quantum levels with plateaux at n2e2/h, where n is an integer, e is the fundamental unit of charge and h is Planck’s constant. However, as the carrier concentration is reduced, the quantised levels show a behaviour that is indicative of the formation of a zig-zag structure and new quantised plateaux appear at low temperatures. In units of 2e2/h the new quantised levels correspond to values of n = 1/4 reducing to 1/8 in the presence of a strong parallel magnetic field which lifts the spin degeneracy but does not quantise the wavefunction. A further plateau is observed corresponding to n = 1/32 which does not change in the presence of a parallel magnetic field. These values indicate that the system is behaving as if charge was fractionalised with values e/2 and e/4, possible mechanisms are discussed.

  • Publication: J. Phys.: Condens. Matter 30 (2018) 09LT01
  • DOI: https://doi.org/10.1088/1361-648X/aaabab
Tue 12 Mar 2019, 15:04 | Tags: Research