Insulator-metal transitions in the phase Cr-doped and phase undoped thin films
- Aligarh Muslim Univ., Aligarh (India). Dept. of Physics
- UGC-DAE Consortium for Scientific Research, Indore (India)
- Raja Ramanna Centre for Advanced Technology, Indore (India). Nano Science Lab. Materials Science Division
- Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
- Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source
$${\mathrm{VO}}_{2}$$ exhibits several insulating phases (monoclinic $M1,M2$, and triclinic $T)$, and the study of these phases is important for understanding the true nature of the insulator-to-metal transition (IMT) in $${\mathrm{VO}}_{2}$$. These insulating phases have small but discernible crystallographic differences in the vanadium chains forming the dimers. Peculiarities of the electron localizations in the dimerized chains for many of the probes such as NMR make it difficult to characterize the true character of these phases [T. J. Huffman et al., Phys. Rev. B 95, 075125 (2017); J. Pouget et al., Phys. Rev. B 10, 1801 (1974)]. We present structural, electrical, ultrafast-reflectivity, and electronic structure studies of the $$T$$ phase Cr-doped $${\mathrm{VO}}_{2}$$ and the $M1$ phase pure $${\mathrm{VO}}_{2}$$ thin films, both grown by pulsed laser deposition under identical conditions. An intermediate $M2$ structure is observed in the Cr-doped $${\mathrm{VO}}_{2}$$, while the pure $${\mathrm{VO}}_{2}$$ directly goes from the insulating monoclinic $M1$ structure to a metallic rutile $$R$$ structure, manifested by temperature-dependent Raman spectroscopy. Temperature-dependent electronic structure studies utilizing x-ray near-edge absorption spectroscopy reveal that all these insulating phases (monoclinic $M1$ and $M2$ and triclinic $T)$ have similar electronic structures which place these insulating phases into the list of Mott-Hubbard insulators. This is a first combined experimental report on the electronic structure of all the three insulating phases, monoclinic $M1,M2$, and triclinic $$T$$.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States); UGC-DAE Consortium for Scientific Research, Indore (India)
- Sponsoring Organization:
- USDOE; Dept. of Science and Technology (DST) (India); Science and Engineering Research Board (SERB) (India)
- Grant/Contract Number:
- AC02-06CH11357; ECR/2017/000712
- OSTI ID:
- 1493920
- Journal Information:
- Physical Review B, Vol. 98, Issue 7; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Nonstoichiometric Oxygen‐Dependent Microstructures and Phase Transitions in Post‐Annealed Vanadium Dioxides
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journal | April 2019 |
Role of V-V dimerization in the insulator-metal transition and optical transmittance of pure and doped thin films
|
journal | January 2020 |
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