Charge density waves in infinite-layer NdNiO2 nickelates

C., Tam, Charles; Choi, Jaewon; Ding, Xiang; Agrestini, S.; Nag, Abhishek; Wu, Mei; Huang, Bing; Luo, Huiqian; Gao, Peng; García-Fernández, Mirian; Qiao, Liang; Zhou, Kejin

doi:10.1038/s41563-022-01330-1

Cited by 80 publications

(45 citation statements)

References 31 publications

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“…Interestingly, similar faint contrast stripes can be observed in the STEM-HAADF image of other uncapped nickelate samples where CO is reported (Figure S5, Supporting Information, of ref. [6]), but were unnoticed. It further anticipates the connection between CO and these (303) stripes.…”

Section: Real Space Structural Comparisonmentioning

confidence: 99%

Charge Distribution across Capped and Uncapped Infinite‐Layer Neodymium Nickelate Thin Films

Raji,

Krieger,

Viart

et al. 2023

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Charge ordering (CO) phenomena have been widely debated in strongly‐correlated electron systems mainly regarding their role in high‐temperature superconductivity. Here, the structural and charge distribution in NdNiO2 thin films prepared with and without capping layers, and characterized by the absence and presence of CO are elucidated. The microstructural and spectroscopic analysis is done by scanning transmission electron microscopy‐electron energy loss spectroscopy (STEM‐EELS) and hard X‐ray photoemission spectroscopy (HAXPES). Capped samples show Ni1+, with an out‐of‐plane (o‐o‐p) lattice parameter of around 3.30 Å indicating good stabilization of the infinite‐layer structure. Bulk‐sensitive HAXPES on Ni‐2p shows weak satellite features indicating large charge‐transfer energy. The uncapped samples evidence an increase of the o‐o‐p parameter up to 3.65 Å on the thin film top with a valence toward Ni2+ in this region. Here, 4D‐STEM demonstrates (303)‐oriented stripes which emerge from partially occupied apical oxygen. Those stripes form quasi‐2D coherent domains viewed as rods in the reciprocal space with Δqz ≈ 0.24 reciprocal lattice units (r.l.u.) extension located at Q = () and () r.l.u. The stripes associated with oxygen re‐intercalation concomitant with hole doping suggest a possible link to the previously reported CO in infinite‐layer nickelate thin films.

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Section: Real Space Structural Comparisonmentioning

confidence: 99%

Charge Distribution across Capped and Uncapped Infinite‐Layer Neodymium Nickelate Thin Films

Raji,

Krieger,

Viart

et al. 2023

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“…[97] However, CDW phase persists in the undoped NdNiO 2 , while it disappears once developed by a level of 0.2, corresponding to the dip. [98] In addition, no long-range antiferromagnetic (AFM) order is detected in undoped nickelates, in contrast to AFM parent compounds of cuprates. [99,100] Besides, multiband conduction is another prominent feature of nickelates.…”

Section: Elemental Substitutionmentioning

confidence: 99%

Modulations in Superconductors: Probes of Underlying Physics

et al. 2023

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development of various modulations techniques, breakthroughs in quantum materials are achieved, such as the quantum anomalous Hall effect (AHE) in topological insulators, [1][2][3][4] gate-tuned roomtemperature ferromagnetism in 2D van der Waals materials, [5][6][7][8] and emergent magnetic monopoles in artificial spin ice. [9] Especially, as the quantum materials of particular interest with zero dissipation, superconductors have been intensively studied with advanced modulations, aiming to reveal a plethora of emergent phenomena in condensed matter physics, such as superconductor-to-insulator transitions (SIT), [10][11][12] intermediate bosonic metallic state, [13] Bose-Einstein condensation (BEC)-Bardeen-Cooper-Schrieffer (BCS) crossover, [14,15] and intertwined orders, [16][17][18] as well as to develop applications in quantum computing [19][20][21] and ultrasensitive detections. [22][23][24] The superconductivity composes of two ingredients, including the Cooper pairs, each formed by two electrons, and phase coherence among Cooper pairs. [25] Superconductors such as metals and alloys are in the weak-coupling regime, which is well understood by BCS theory. [26,27] However, the later discovered superconductors, including cuprates, iron-based superconductors, and heavy-fermion superconductors, are strongly correlated systems, where a widely accepted microscopic mechanism yet remains absent. Therefore, various modulations have been utilized for the ultimate understanding of these superconductors and routines for room temperature superconductivity. Traditional modulations, such as elemental substitution, annealing, and polarization-induced gating are usually accompanied by some severe problems, including discontinuity, disorders, and limited ranges. Recently, state-of-the-art techniques have been developed with improved convenience, increased capability, and unprecedented dimensionalities, enabling more thorough investigations of unconventional superconductors.As a manifestation, we take some examples discussed in this review in advance. The carrier density can be tuned more conveniently and continuously. The techniques of ionic field-effect transistor (iFET) and electric double-layer transistor (EDLT) surpass conventional methods limited by solid solubility or dielectric breakdown, which enables the more precise phase diagram and detailed scaling analysis at the quantum phaseThe importance of modulations is elevated to an unprecedented level, due to the delicate conditions required to bring out exotic phenomena in quantum materials, such as topological materials, magnetic materials, and superconductors. Recently, state-of-the-art modulation techniques in material science, such as electric-double-layer transistor, piezoelectric-based strain apparatus, angle twisting, and nanofabrication, have been utilized in superconductors. They not only efficiently increase the tuning capability to the broader ranges but also extend the tuning dimensionality to unprecedented degrees of freedom, including quantum fluctuations of...

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“…140 Previously, charge density waves have been observed in numerous strongly correlated materials. [135][136][137][140][141][142][143] For example, charge density waves have been observed in high-T c superconductors. 25,137,144,145 The electron-phonon coupling in charge density waves and their relationship with other quantum phenomena, such as unconventional superconductivity, remain open questions and have attracted intensive research.…”

Section: (B) Coherent Phonon Dynamicsmentioning

confidence: 99%