Low dimensional Conductors and Magnets

The Science behind the research

Electronic transport in dimensions below three can have unique properties, often driven by enhanced densities of states at the chemical potential. Not only is the transport inherently anisotropic but also exotic properties like spin-density waves and spin/charge separation have been observed.

Ongoing research

We are interested in two materials K_0.3MoO₃ (blue bronze) and La-doped Sr₂IrO₄ [see publication below]. Blue bronze is a 1D conductor that is predicted to have spinon and holon excitations (as in a Luttinger liquid) that we hope to observe with neutron scattering and Sr₂IrO₄ is a 2D antiferromagnet with pseudogaps excitations very similar to the cuprate high temperature superconductors.

Figure 1 below shows (a) an Experimental Fermi surface of (Sr_0.935La_0.065)₃Ir₂O₇ taken with hν=83 eV at 8 K. We denote the (π,0) point of the two-dimensional Ir sublattice by X and the (π/2,π/2) point by M. (b),(c) Photoemission intensity along the ΓM and ΓX high symmetry directions, respectively. (d) Stack of energy distribution curves around the Fermi surface extracted from the data shown in panel (b).

Fig 1. Low energy excitations in lightly doped Sr3Ir2O7 measured by Angle Resolved Photoemission Spectroscopy (ARPES) at Diamond, Harwell.

Low energy excitations in lightly doped Sr3Ir2O7.jpg

Recent Publications

Coherent Quasiparticles with a Small Fermi Surface in Lightly Doped Sr3Ir2O7, de la Torre et al. Physical Review Letters 113, 256402 (2014)