Electronic structure of commensurate, nearly commensurate, and incommensurate phases of 
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 by angle-resolved photoelectron spectroscopy, scanning tunneling spectroscopy, and density functional theory

Lutsyk, Iaroslav; Rogala, Maciej; Dąbrowski, P.; Krukowski, Pawel; Kowalczyk, P.; Busiakiewicz, A.; Kowalczyk, Dorota A.; Lacinska, Ewa; Binder, Johannes; Olszowska, Natalia; Kopciuszyński, M.; Szałowski, K.; Gmitra, Martin; Stępniewski, R.; Jałochowski, M.; Kołodziej, Jacek; Wysmołek, A.; Klusek, Z.

doi:10.1103/physrevb.98.195425

Cited by 33 publications

(28 citation statements)

References 46 publications

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“…Furthermore, a detailed microscopic inspection allows us to witness a region, which exhibits an intriguing pattern of segregated charge density modulations. A similar nature of charge density modulation has been reported for various CDW materials 44 – 46 . The segregated charge density presumably manifest the highly localized Coulomb interaction 47 .…”

Section: Resultssupporting

confidence: 81%

Coexisting commensurate and incommensurate charge ordered phases in CoO

Negi

Singh

Ahuja

et al. 2021

Sci Rep

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The subtle interplay of strong electronic correlations in a distorted crystal lattice often leads to the evolution of novel emergent functionalities in the strongly correlated materials (SCM). Here, we unravel such unprecedented commensurate (COM) and incommensurate (ICOM) charge ordered (CO) phases at room temperature in a simple transition-metal mono-oxide, namely CoO. The electron diffraction pattern unveils a COM ($$q_{1}$$ q 1 =$$\frac{1}{2}(1,1,{\bar{1}})$$ 1 2 ( 1 , 1 , 1 ¯ ) and ICOM ($$q_{2}=0.213(1,1,{\bar{1}})$$ q 2 = 0.213 ( 1 , 1 , 1 ¯ ) ) periodic lattice distortion. Transmission electron microscopy (TEM) captures unidirectional and bidirectional stripe patterns of charge density modulations. The widespread phase singularities in the phase-field of the order parameter (OP) affirms the abundant topological disorder. Using, density functional theory (DFT) calculations, we demystify the underlying electronic mechanism. The DFT study shows that a cation disordering ($$\mathrm {Co}_{1-\textit{x}}\mathrm {O}, \text {with }{} \textit{x} = 4.17 \%$$ Co 1 - x O , with x = 4.17 % ) stabilizes Jahn-Teller (JT) distortion and localized aliovalent $$\mathrm {Co}^{3+}$$ Co 3 + states in CoO. Therefore, the lattice distortion accompanied with mixed valence states ($$\mathrm {Co}^{3+}, \mathrm {Co}^{2+}$$ Co 3 + , Co 2 + ) states introduces CO in CoO. Our findings offer an electronic paradigm to engineer CO to exploit the associated electronic functionalities in widely available transition-metal mono-oxides.

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Section: Resultssupporting

confidence: 81%

Coexisting commensurate and incommensurate charge ordered phases in CoO

Negi

Singh

Ahuja

et al. 2021

Sci Rep

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“…( This energy scale is similar to the C-CDW gap shown through various experiments [17,29]. This indicates that one of the phases is the C-CDW phase.…”

Section: T Csupporting

confidence: 76%

Hidden electronic phase in strained few-layer 1T−TaS2

Sruthi

Kundu

Prasad

et al. 2021

Phys. Rev. Materials

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Layered van der Waals materials are exciting as they often host multiple, competing electronic phases. This article reports the experimental observation of the coexistence of insulating and metallic phases deep within the commensurate charge density wave phase in high-quality devices of few-layer 1T-TaS 2 . Through detailed conductance fluctuation spectroscopy of the electronic ground state, we establish that the mixed phase consists of insulating regions surrounded by one-dimensional metallic domain walls. We show that the electronic ground state of 1T-TaS 2 can be affected drastically by strain, eventually leading to the collapse of the Mott gap in the commensurate charge density wave phase. Our study resolves an outstanding question, namely the effect of the interlayer coupling strength on the electronic phases in layered van der Waals materials.

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“…The scanning tunneling spectroscopy shows that while the energy splitting between the lower Hubbard peak and the upper Hubbard peak at 5 K [18] and 78 K [19] appears to fall on our E BO g (T ) curve, some in-gap density of states has emerged at the elevated temperature. At 130 K [20], the gap profile has transformed into a V shape. On the other hand, a recent nuclear quadruple resonance measurement [12] shows that below T CCDW , the spin-lattice relaxation rate 1/T 1 undergoes an anomalous transition from T 2 to a much steeper T 4 power law.…”

Section: Discussionmentioning

confidence: 99%

“…The Mott phase in 1T-TaS 2 features (i) geometry frustration, (ii) a soft gap of the order of 10 2 meV [18][19][20], and (iii) the accompanying lattice distortion. Current investigations largely concentrate on the first two aspects.…”

Section: Introductionmentioning

confidence: 99%

Renormalization of the Mott gap by lattice entropy: The case of 1T- TaS2

Cheng

Zhang

Qiao

et al. 2020

Phys. Rev. Research

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In many transition-metal oxides and dichalcogenides, the electronic and lattice degrees of freedom are strongly coupled, giving rise to remarkable phenomena such as the metal-insulator transition (MIT) and charge-density wave (CDW) order. We study this interplay by tracing the instant electronic structure under ab initio molecular dynamics. Applying this method to a 1T-TaS 2 layer, we show that the CDW-triggered Mott gap undergoes a continuous reduction as the lattice temperature rises, despite a nearly constant CDW amplitude. Before the CDW order undergoes a sharp first-order transition around the room temperature, the dynamical CDW fluctuation shrinks the Mott gap size by half. The gap size reduction is one order of magnitude larger than the lattice temperature variation. Our calculation not only provides an important clue to understanding the thermodynamic behavior in 1T-TaS 2 , but also demonstrates a general approach to quantify the lattice entropy effect in the MIT.

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Electronic structure of commensurate, nearly commensurate, and incommensurate phases of 1T−TaS2 by angle-resolved photoelectron spectroscopy, scanning tunneling spectroscopy, and density functional theory

Cited by 33 publications

References 46 publications

Coexisting commensurate and incommensurate charge ordered phases in CoO

Coexisting commensurate and incommensurate charge ordered phases in CoO

Hidden electronic phase in strained few-layer 1T−TaS2

Renormalization of the Mott gap by lattice entropy: The case of 1T- TaS2

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