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Probing Spin-Charge Separation in a Tomonaga-Luttinger Liquid

Science  31 Jul 2009:
Vol. 325, Issue 5940, pp. 597-601
DOI: 10.1126/science.1171769

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Electron Breakdown

An electron possesses charge and spin. In general, these properties are confined to the electron. However, in strongly interacting many-body electronic systems, such as one-dimensional wires, it has long been theorized that the charge and spin should separate. There have been tantalizing glimpses of this separation experimentally, but questions remain. Jompol et al. (p. 597) looked at the tunneling current between an array of one-dimensional wires and a two-dimensional electron gas and argue that the results reveal a clear signature of spin-charge separation.

Abstract

In a one-dimensional (1D) system of interacting electrons, excitations of spin and charge travel at different speeds, according to the theory of a Tomonaga-Luttinger liquid (TLL) at low energies. However, the clear observation of this spin-charge separation is an ongoing challenge experimentally. We have fabricated an electrostatically gated 1D system in which we observe spin-charge separation and also the predicted power-law suppression of tunneling into the 1D system. The spin-charge separation persists even beyond the low-energy regime where the TLL approximation should hold. TLL effects should therefore also be important in similar, but shorter, electrostatically gated wires, where interaction effects are being studied extensively worldwide.

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