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 Yittrium 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 Y2−xBixIr2O7 with x = 0 and 0.3. 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 frequency and temperature regime. The evidence of 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.

Negative Longitudinal Magnetoresistance in the Density Wave Phase of Y2Ir2O7Juyal1, Agarwal2, Mukhopadhyay3 2018Phys. Rev. Lett.Self Cite283230View full textAdd to dashboardCite

“…1(f), we show the real and imaginary part of the low frequency dielectric response (related to the ac conductivity via the relation iω (ω) = σ(ω) − σ 0 , where σ 0 denotes the dc conductivity) for several temperatures (from 80 K to 290K). Similar dielectric response for YBIO nanowire was reported earlier [15]. The dielectric response at different temperatures [see Fig.…”

“…The origin of nonlinear transport including hysteretic switching in CDW has been discussed earlier [20][21][22][23][24]. The non-linear conduction, the switching behaviour and the associated threshold V T can be dramatically tuned by changing the cooling rate [15]. On rare occasions, we observe colossal enhancement of conductivity over the entire temperature range, when the sample is cooled sufficiently rapidly (see Fig.…”

“…In a recent work, we demonstrated the existence of charge density wave (CDW) order in single crystalline nanowires of Pyrochlore Iridates [15]: Y 2−x Bi x Ir 2 O 7 with x = 0 (YIO) and 0.3 (YBIO). However, the physical origin of the observed CDW instability in YIO and YBIO is not clear.…”

“…Single crystalline nanowires of YIO were prepared following the method of [15,17], and drop casted on silicon oxide substrate with subsequent metallization using e-beam lithography -see Fig. 1(f).…”

Suppression of long range magnetic ordering and electrical conduction in Y1.7Bi0.3Ir2<

“…The interplay between comparable energy scales, namely the strong relativistic spin-orbit coupling (SOC), crystal field effect and on site Coulomb repulsion giving rise to novel topological phases makes the 5d iridate systems fundamentally interesting [1,2,3,4,5,6,7], with promising applications in quantum computing and spin based electronics [8]. The ratio of the energy scales between electronic correlation and kinetic hopping can be effectively tuned by chang-ing the A-site ionic radius in pyrochlore iridates with general formula A 2 Ir 2 O 7 (where A = Y, Bi or rare earth ions) [5], leading to metal insulator transition which is often accompanied by a paramagnetic to an antiferromagnetic (AFM) phase transition [9].…”