Hysteretic Melting Transition of a Soliton Lattice in a Commensurate Charge Modulation

Abstract

We report on the observation of the hysteretic transition of a commensurate charge modulation in IrTe 2 from transport and scanning tunneling microscopy (STM) studies. Below the transition (T C ≈ 275 K on cooling), a q ¼ 1=5 charge modulation was observed, which is consistent with previous studies. Additional modulations [q n ¼ ð3n þ 2Þ −1 ] appear below a second transition at T S ≈ 180 K on cooling. The coexistence of various modulations persists up to T C on warming. The atomic structures of charge modulations and the temperature-dependent STM studies suggest that 1=5 modulation is a periodic soliton lattice that partially melts below T S on cooling. Our results provide compelling evidence that the ground state of IrTe 2 is a commensurate 1=6 charge modulation, which originates from the periodic dimerization of Te atoms visualized by atomically resolved STM images.

Charge-ordering cascade with spin–orbit Mott dimer states in metallic iridium ditelluride

“…One can notice gradual increase of the peak intensity in heating, especially from 200 to 280 K, mainly due to improvement of the modulation regularity. An additional 1/11 ordering of a minor faction was observed in LT phase in the scanning tunnelling microscope (STM) 19 . However, any hint of this order is not observable in the XRD, indicating that it is a surface phenomenon.…”

Nanoscale Superconducting Honeycomb Charge Order in IrTe2

“…In this study, we identify with STM a unprecedented honeycomb charge ordering in nanoscale coexistence with stripe charge orders of IrTe2 [19][20][21][22][23][24] , which is distinct from the hexagonal CDW.…”

“…IrTe2 is currently under extensive investigations due to its unusual electronic properties related to the charge ordering. IrTe2 is an outstanding transition metal dichalcogenide with a charge order (Ir 5d 3+ -Ir 5d 4+ ) transition into 4 stripe phases with a large hysteresis and a nontrivial remnant metallic conductivity [19][20][21][22][23]25,26 .…”

“…1e) [21][22][23] . In extra, we find another distinct phase with a hexagonal symmetry as enclosed by stripe phases of three different orientations on the surface below the transition temperature.…”

Bond competition and phase evolution on the IrTe2 surface

“…Both the HT and LT phases of IrTe 2 show significant threedimensional electronic structures reflecting interactions (and in the case of the LT phase, bonding) between adjacent CdI 2 structure layers, which is very different from most layered dichalcogenides, which are generally more two dimensional and show real CDW instabilities 10 . Several scanning tunnelling microscope (STM) studies 11,12 have been reported recently on IrTe 2 , but the relationship between the structural and electronic properties remains to be fully elucidated. In any case, the fact that the transition is associated with Te-Te bonding with interlayer bonds suggests that the surface may favour a different pattern than the bulk leading to a competition.…”