Emergent Network of Narrow Transport Channels
A new route for a metal to insulator transition, driven by the
creation of a network of narrow channels, has been discovered.
When Pt is substituted for Ti in 1T-TiSe2 (panel (a)), a self-doped
charge-density wave material, the resistivity shows a dramatic
increase by five orders of magnitude (panel (b)). Akin to a stone
creating cracks in an ice-sheet, the impact of Pt creates domain walls
(panel (c),(d)) of nanometer size diameter that suck charge from the
bulk leaving a hard insulating gap in the bulk (panel (e), scan (1)).
The charges now confined to narrow channels interact strongly
forming a pseudogap, similar to a Luttinger liquid, as seen in the local
density of states by scanning tunneling spectroscopy (STM) (panel
(e), scan (3,4)), and further corroborated by angle resolved
photoemission spectroscopy (ARPES) that shows a pseudogap
opening up at the L-point at low temperatures.