Structural phase transition associated with van Hove singularity in 5d transition metal compound IrTe2

T Qian,H Ding,X Shi,J Z Ma,H Miao,P Richard,Z Fang,L K Zeng,Z J Wang,Y B Huang,N L Wang,P Zhang,M Shi,N Xu,G Xu,A F Fang,X Dai

doi:10.1088/1367-2630/16/12/123038

Abstract

We have investigated the electronic states of IrTe2 by using angle-resolved photoemission spectroscopy to elucidate the origin of the structural phase transition. Both the Ir 4f and Te 4d core level spectra exhibit dramatic splitting below the phase transition temperature Ts, suggesting that there exist two inequivalent Ir and Te sites with distinctly different electronic states in the distorted phase. The band related to the saddle points at the Fermi level (EF) is strongly reconstructed, which removes the van Hove singularity from EF below Ts. The wavevector connecting the adjacent saddle points is consistent with the in-plane superstructure modulation wavevector. These results indicate that the phase transition in IrTe2 is intimately associated with the saddle points. As the van Hove singularity mainly originates from the Te px+py orbitals, the Te 5p electronic states play a dominant role in the structural phase transition.

Highlights

We reveal that the phase transition in IrTe2 is intimately associated with the van Hove singularity at the Fermi level (EF)
The van Hove singularity (vHs) arises from the saddle points around the Brillouin zone boundary and the wavevector between the adjacent saddle points is q ∼ (1 5, 0, 0), which is consistent with the in-plane structural modulation wavevector
To inspect whether there exists any energy gap induced by this nesting, we show in figures 3(d) and (e) the Angleresolved photoemission spectroscopy (ARPES) spectra along the kx = −0.55 Å−1 cut at 300 and 30 K, respectively

Summary

Introduction

We reveal that the phase transition in IrTe2 is intimately associated with the van Hove singularity (vHs) at the Fermi level (EF). The band related to the saddle points is dramatically reconstructed below Ts, leading to a significant reduction of the electronic energy, which is likely to be the driving force for the transition.

Results

Conclusion