Superconductivity emerging from a stripe charge order in IrTe2 nanoflakes

Sungyu Park,Sang-Wook Cheong,Sooran Kim,Gyu Seung Choi,Kenji Watanabe,Tae-Hwan Kim,Takashi Taniguchi,Evgeny F Talantsev,Jun Sung Kim,C J Won,Taeho Kim,Kyoo Kim,Hyoung Kug Kim,B J Kim,H W Yeom,Jonghwan Kim,Min Jeong Kim,Hoon Kim,So Young Kim

doi:10.1038/s41467-021-23310-w

Abstract

Superconductivity in the vicinity of a competing electronic order often manifests itself with a superconducting dome, centered at a presumed quantum critical point in the phase diagram. This common feature, found in many unconventional superconductors, has supported a prevalent scenario in which fluctuations or partial melting of a parent order are essential for inducing or enhancing superconductivity. Here we present a contrary example, found in IrTe2 nanoflakes of which the superconducting dome is identified well inside the parent stripe charge ordering phase in the thickness-dependent phase diagram. The coexisting stripe charge order in IrTe2 nanoflakes significantly increases the out-of-plane coherence length and the coupling strength of superconductivity, in contrast to the doped bulk IrTe2. These findings clarify that the inherent instabilities of the parent stripe phase are sufficient to induce superconductivity in IrTe2 without its complete or partial melting. Our study highlights the thickness control as an effective means to unveil intrinsic phase diagrams of correlated van der Waals materials.

Highlights

Superconductivity in the vicinity of a competing electronic order often manifests itself with a superconducting dome, centered at a presumed quantum critical point in the phase diagram
Upon chemical doping[4,5,7,8], these phases are commonly driven into a superconducting phase, resulting in a characteristic domeshaped phase diagram, reminiscent of those found in other unconventional superconductors[9,10,11] (Fig. 1a)
Using Raman spectroscopy, scanning tunnelling microscopy, and transport property measurements, we found that the parent stripe phase encompasses the whole superconducting dome in the thicknessdependent phase diagram (Fig. 1a)

Summary

Introduction

Superconductivity in the vicinity of a competing electronic order often manifests itself with a superconducting dome, centered at a presumed quantum critical point in the phase diagram. Utilising the weak van der Waals (vdW) coupling between layers, TMDCs were found to be thinned down to atomic length scale[12], comparable with the coherence lengths of their various electronic orders This offers another effective way to tune stability or properties of the competing phases, as demonstrated for 1T-TaS213–15 and NbSe216,17, in which distinct thickness dependence of the transition temperatures is observed for superconducting and CDW phases. Using Raman spectroscopy, scanning tunnelling microscopy, and transport property measurements, we found that the parent stripe phase encompasses the whole superconducting dome in the thicknessdependent phase diagram (Fig. 1a) This unusual coexistence of the stripe and superconducting orders significantly increases the interlayer coherence length and the coupling strength of superconductivity in IrTe2 nanoflakes, revealing the collaborative role of the stripe order to the superconductivity in IrTe2

Methods

Results

Conclusion