Evidence of density waves in single-crystalline nanowires of pyrochlore iridates

Abstract

We present experimental evidence of emergent density-wave instability in single-crystalline low-dimensional wires of yttrium-based pyrochlore iridates. We demonstrate electric-field-induced nonlinear hysteretic switching of the density wave at low temperature, followed by smooth nonlinear conduction at higher temperature $(T>40$ K) in ${\mathrm{Y}}_{2\ensuremath{-}x}{\mathrm{Bi}}_{x}{\mathrm{Ir}}_{2}{\mathrm{O}}_{7}$, with $x=0$ and 0.3. The ac transport measurements reveal the presence of four different collective relaxation processes which dominate at different temperature scales. There is a strong coupling of the normal charge carriers with the density-wave condensate, which is reflected in the linear scaling of the dc conductivity with the collective relaxation rate across a wide range of frequencies and temperatures. The evidence of the density wave in low-dimensional single crystals of pyrochlore iridate could be a precursor to the possible experimental confirmation of the Weyl semimetallic ground state with broken chiral symmetry.