Phase evolution with the film thickness in PLD-grown titanium oxides films

Feng, Jinchao; Wang, Lingling; Song, Yekai; Yu., A Filimonov; Li, Wei; Zhang, Han; Wang, Teng; Chu, J. J.; Xu, Xuguang; Peng, Wei; Li, Zhuojun; Mu, Gang

doi:10.1016/j.jallcom.2020.154727

Cited by 4 publications

(5 citation statements)

References 23 publications

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“…The Ti 2 O 3 thin films are grown on a (0001)-oriented GaN substrate with an N-polar terminated face by pulsed laser deposition. X-ray diffraction measurements suggest the as-grown Ti 2 O 3 film to be polycrystalline with an admixture of corundum and orthorhombic polymorphs (Figure S2), in agreement with previous studies. , The microstructure of the interface of Ti 2 O 3 /GaN is also examined by aberration-corrected scanning transmission electron microscopy (STEM). From the high angle annular dark field (HAADF)-STEM image shown in Figure A, an abrupt interface between an annealed GaN surface and the polycrystalline Ti 2 O 3 overlayer could be clearly resolved.…”

Section: Resultssupporting

confidence: 89%

“…X-ray diffraction measurements suggest the asgrown Ti 2 O 3 film to be polycrystalline with an admixture of corundum and orthorhombic polymorphs (Figure S2), in agreement with previous studies. 21,22 The microstructure of the interface of Ti 2 O 3 /GaN is also examined by aberrationcorrected scanning transmission electron microscopy (STEM).…”

Section: Resultsmentioning

confidence: 99%

“…20,21 The threedimensional isotropic superconductivity in the Ti 2 O 3 /Al 2 O 3 heterostructure has also been revealed by angular-dependent upper critical fields. 22 Notably, the charge carrier concentration is found as high as 10 21 cm −3 in the orthorhombic Ti 2 O 3 / Al 2 O 3 , 21 which is approximately one order larger than that of corundum films, demonstrating that a large amount of oxygen vacancy induced electron-like charge carriers drive the Mott insulator Ti 2 O 3 into a superconductivity.…”

mentioning

confidence: 99%

“…Titanium oxides are a large family of transition metal materials with many fascinating and appealing electrical properties and have potential applications as a consequence of the variable oxidation states associated with strong structure–property correlations. − Among them, titanium sesquioxide Ti 2 O 3 is a typical antiferromagnetic Mott insulator with strong electron correlation and a narrow-band gap of 0.1 eV as a result of partial filling of the Ti 3d 1 band ( S = 1/2), , which is similar to the configuration in the Mott insulator LaTiO 3 , and indicates promise as a candidate unconventional superconductor driven by electron correlation effects upon charge carrier injection . Interestingly, the superconductivity has been experimentally observed in Ti 2 O 3 polymorphic films with the orthorhombic phase epitaxially grown on the α-Al 2 O 3 substrates, whereas the corundum phase of Ti 2 O 3 polymorphic films remains an insulator, in recent years. , The three-dimensional isotropic superconductivity in the Ti 2 O 3 /Al 2 O 3 heterostructure has also been revealed by angular-dependent upper critical fields . Notably, the charge carrier concentration is found as high as 10 21 cm –3 in the orthorhombic Ti 2 O 3 /Al 2 O 3 , which is approximately one order larger than that of corundum films, demonstrating that a large amount of oxygen vacancy induced electron-like charge carriers drive the Mott insulator Ti 2 O 3 into a superconductivity.…”

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confidence: 99%

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Two-Dimensional Superconductivity at the Titanium Sesquioxide Heterointerface

Wang

Huang

et al. 2022

ACS Nano

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The study of exotic superconductivity in two dimensions has been a central theme in the solid state and materials research communities. Experimentally exploring and identifying exotic, fascinating interface superconductors with a high transition temperature (T c) are challenging. Here, we report an experimental observation of intriguing two-dimensional superconductivity with a T c of up to 3.8 K at the interface between a Mott insulator Ti2O3 and polar semiconductor GaN. At the verge of superconductivity, we also observe a striking quantum metallic-like state, demonstrating that it is a precursor to the two-dimensional superconductivity as the temperature is decreased. Our work shows an exciting opportunity to exploit the underlying, emergent quantum phenomena at the heterointerfaces via heterostructure engineering.

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Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Two-Dimensional Superconductivity at the Titanium Sesquioxide Heterointerface

Wang

Huang

et al. 2022

ACS Nano

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“…[7,8] A model system for investigating disorder-induced phase transitions is the binary titanium oxide (Ti x O y ) system. [9][10][11][12] Ti x O y can crystallize in a wide range of crystal structures that depend on the Ti/O ratio and growth conditions. [13,14] Ti x O y bulk and thin films exhibit a wide range of electronic properties ranging from metallic and insulating phases to superconductivity.…”

mentioning

confidence: 99%

In Situ Scattering Studies of Superconducting Vacancy‐Ordered Monoclinic TiO Thin Films

Baksi,

Hong,

Kumah

2023

Advanced Physics Research

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The structural and transport properties of vacancy‐ordered monoclinic superconducting titanium oxide (TiO) thin films grown by molecular beam epitaxy are investigated. The evolution of the crystal structure during growth is monitored by in situ synchrotron X‐ray diffraction. Long‐range ordering of Ti and O vacancies in the disordered cubic phase stabilizes the vacancy‐ordered monoclinic TiO phase. The reduced structural disorder arising from vacancy‐ordering is correlated with a superconductor‐metal transition (SMT) in contrast to the superconductor‐insulator transition (SIT) observed in cubic TiO, orthorhombic Ti2O3, and the Magneli γ − Ti3O5 and γ − Ti4O7 phase. Magnetoresistance measurements for the SIT phases indicate superconducting fluctuations persisting in the normal phase. These results confirm the role of disorder related to Ti and O vacancies and structural inhomogeneity in determining the electronic properties of the normal state of titanium oxide‐based superconductors.

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