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

Abstract

Spin-orbit coupling results in technologically-crucial phenomena underlying magnetic devices like magnetic memories and energy-efficient motors. In heavy element materials, the strength of spin-orbit coupling becomes large to affect the overall electronic nature and induces novel states such as topological insulators and spin-orbit-integrated Mott states. Here we report an unprecedented charge-ordering cascade in IrTe 2 without the loss of metallicity, which involves localized spin-orbit Mott states with diamagnetic Ir 4 þ -Ir 4 þ dimers. The cascade in cooling, uncompensated in heating, consists of first order-type consecutive transitions from a pure Ir 3 þ phase to Ir 3 þ -Ir 4 þ charge-ordered phases, which originate from Ir 5d to Te 5p charge transfer involving anionic polymeric bond breaking. Considering that the system exhibits superconductivity with suppression of the charge order by doping, analogously to cuprates, these results provide a new electronic paradigm of localized charge-ordered states interacting with itinerant electrons through large spin-orbit coupling.

Moiré Superstructure and Dimensional Crossover of 2D Electronic States on Nanoscale Lead Quantum Films

“…Their origins are commonly the charge ordering of Ir 5 d 3+ and 5 d 4+ , which accompanies substantial lattice distortions through the Ir dimerization. The dominant phase is the stripe phase of a 5a 0 period, which is mixed with other stripes of a 3a 0 or 8a 0 period as reported previously 13 – 24 . On the other hand, the minor phase of a hexagonal pattern has a period of about 7.4a 0 and falls into a superconducting state below 3.1 K 29 .…”

“…2D quantum well states (QWS’s) of Pb films are found to be modulated laterally by the Moiré superstructure at the interface. Furthermore, the substrate features a transition into charge-ordered ground states 13 – 24 with emergent superconductivity 25 – 28 . The stripe charge ordering and the lattice distortion accompanied provide an extra tunability into the 2D electronic states, that is, the 2D-1D dimensional crossover of electronic states.…”

Thermal diodes, regulators, and switches: Physical mechanisms and potential applications

“…Lee et al 24 interpret the data as indicating that the electrons in the metallic state of VO 2 tend to recover the WF behavior as the W doping increases. Other materials displaying metal-insulator 27 or metal-metal 28 transitions may also be promising thermal regulators; for example, a ferromagnetic magnetite material 29 has shown r ¼ 1.5 across a MIT at 200 K.…”

Charge-Stripe Order and Superconductivity in Ir1−xPtxTe2

“…Charge ordering of the parent compound has been studied in great detail, and it has been shown how different modulation vectors emerge as a function of temperature. Upon cooling the system first develops a (1/5, 0, 1/5) modulation ( T < 280 K) that switches to (1/8, 0, 1/8) at lower temperatures 24 – 26 , ( T < 200 K). There exist, however, no x-ray diffraction studies of the charge order in Ir 1−x Pt x Te 2 near the critical composition ( x c ~ 0.045) for superconductivity.…”

“…Just below this critical composition, we find a temperature independent charge ordering modulation vector (1/5, 0, 1/5). This signifies a difference from the parent compound where the ground state charge modulation is (1/8, 0, 1/8) 25 , 26 . Our pressure experiments were carried out just above x c (namely at x = 0.05) in a compound with a superconducting ground state and no evidence of charge order at, and around, ambient conditions 1–400 bar.…”