Vacancies and superconductivity in titanium monoxide

Doyle, N; Hülm, J. K.; Jones, C. K.; Miller, R. C.; Taylor, A. J.

doi:10.1016/0375-9601(68)90146-1

Cited by 56 publications

(19 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The T C of Ti 4 O 7 and γ -Ti 3 O 5 were 3.0 K and 7.1 K for T C,onset , 2.7 K and 6.6 K for T C,mid , and 5.8 K and 2.5 K for T C,zero , respectively. Note that the T C of both films exceeded that of other simple-oxide superconductors in bulk [TiO ( T C = 2.3 K), NbO ( T C ~1.4 K), and SnO ( T C = 1.4 K under 9.3 GPa)] 13–16 . We also note that enhancement of T C = ~7 K in TiO films has been reported in recent 17 .…”

Section: Resultsmentioning

confidence: 84%

Superconductivity in Ti4O7 and γ-Ti3O5 films

Yoshimatsu

Sakata

Ohtomo

2017

Sci Rep

View full text Add to dashboard Cite

Titanium dioxide is one of the most popular compounds among simple oxides. Except for the fully oxidized titanate, titanium oxides have partially filled d states and their exotic properties have captured attention. Here, we report on the discovery of superconductivity in Ti 4 O 7 and γ-Ti 3 O 5 in a thin film form. The epitaxial Ti 4 O 7 and γ-Ti 3 O 5 thin films were grown using pulsed-laser deposition on (LaAlO 3 ) 0.3 -(SrAl 0.5 Ta 0.5 O 3 ) 0.7 and α-Al 2 O 3 substrates, respectively. The highest superconducting transition temperatures are 3.0 K and 7.1 K for Ti 4 O 7 and γ-Ti 3 O 5 , respectively. The mechanism behind the superconductivity is discussed on the basis of electrical measurements and previous theoretical predictions. We conclude that the superconductivity arises from unstabilized bipolaronic insulating states with the assistance of oxygen non-stoichiometry and epitaxial stabilization.In the periodic table, titanates are the first group of simple oxides, which are defined as oxides consisted of a kind of the cation and oxygen ion(s), indicating metallicity, and all the simple oxides of scandium or much lighter elements are insulating. Therefore, the choice of titanates is favourable for large electron-phonon coupling. 1,2 that exhibits unique low-dimensional structures characterized by shear planes. These shear planes correspond to the rutile TiO 2 (121) planes and amputate the edge-shared infinite TiO 6 chains at every n TiO 6 blocks with shifting by a half of the unit cell. In the nominal composition, a TiO 6 tetramer has two electrons occupying the Ti 3d states. Trititanium pentoxide (Ti 3 O 5 ) with polymorphisms (α-, β−, γ−, δ−, and λ-phases) is a neighbour of the Magnéli phase 3-7 . γ-Ti 3 O 5 is one of them with a monoclinic cell (a = 5.0747 Å, b = 9.9701 Å, c = 7.1810 Å, α = 109.865°)4 . In contrast to the Magnéli phase, there are no shear planes, as illustrated in Fig. 1(b). However, since the chemical formula is consistent with that of the Magnéli phase (Ti n O 2n-1 at n = 3), it is sometimes designated as the first member of the Magnéli phase. Because of difficulty in the growth of a single crystal due to polymorphism, their physical properties are still under debate. Several studies have dealt with the structural phase transitions accompanying MIT, which are induced under the specific conditions (α ↔ β at 450 K 3 , δ ↔ γ at 240 K 4-7 , and β ↔ λ by irradiation using visible-light pulses 6 ). We find that Ti 4 O 7 and γ-Ti 3 O 5 films synthesized using epitaxial growth are superconductors with T C s 3.0 K and 7.1 K, respectively. The temperature dependence of resistivity strongly depended on the growth atmosphere. The Ti 4 O 7 film grown under a more oxidation condition of oxygen atmosphere exhibited metal-insulator transition (MIT) accompanied by clear hysteresis at ~150 K. The insulating phase was suppressed in the films grown under a less oxidative condition of Ar atmosphere, and the superconducting phase appeared at low temperatures. These results and the previous theoretical predi...

show abstract

Section: Resultsmentioning

confidence: 84%

Superconductivity in Ti4O7 and γ-Ti3O5 films

Yoshimatsu

Sakata

Ohtomo

2017

Sci Rep

View full text Add to dashboard Cite

show abstract

“…Even when x = 1.0, Ti sites may be vacant randomly. It exhibits superconductivity at Tc = 2.3 K [317], while the one with vacancies [85,86]. The stoichiometric zero vacancy oxide was prepared under the high pressure of 77kbar (7.7Gpa) at 1923K [316].…”

Section: The Nacl Structurementioning

confidence: 99%

Electronic Conduction in Oxides

Tsuda

Nasu

Fujimori

et al. 2000

Springer Series in Solid-State Sciences

263

157

View full text Add to dashboard Cite

show abstract

“…[12][13][14][15] In addition, there are some notable transition-metal-oxide superconductors, such as tungsten bronzes with T C values up to 6 K. 16,17 Within the 3d-transition-metal series, Ti + -based compounds are predicted to be promising candidates for high-T C superconductors as a result of their special filling (3d 1 and S = 1/2), 18 but superconducting titanates have been limited to materials like electrondoped SrTiO 3 (T C ≈0.41 K), 19 non-stoichiometric titanium monoxide TiO x (T C ≤ 2.3 K) 20,21 and ternary oxide Li-Ti-O (T C ≈14 K). [22][23][24] Recently, interest in superconducting titanate thin films has resurged, and superconductivity in TiO, 25 ) valence states, and there has been no report of superconductivity in a "pure" Ti 3+ (3d 1 ) system.…”

Section: Introductionmentioning

confidence: 99%

Observation of superconductivity in structure-selected Ti2O3 thin films

Weng

Zhang

et al. 2018

NPG Asia Mater

View full text Add to dashboard Cite

The search for new superconductors capable of carrying loss-free current has been a research theme in condensed matter physics for the past decade. Among superconducting compounds, titanates have not been pursued as much as Cu 2+ (3d 9 ) (cuprate) and Fe 2+ (3d 6 ) (pnictide) compounds. Particularly, Ti 3+ -based compounds or electron systems with a special 3d 1 filling are thought to be promising candidates as high-T C superconductors, but there has been no report on such pure Ti 3+ -based superconducting titanates. With the advent of thin-film growth technology, stabilizing new structural phases in single-crystalline thin films is a promising strategy to realize physical properties that are absent in the bulk counterparts. Herein, we report the discovery of unexpected superconductivity in orthorhombicstructured thin films of Ti 2 O 3 , a 3d 1 electron system, which is in strong contrast to the conventional semiconducting corundum-structured Ti 2 O 3 . This is the first report of superconductivity in a titanate with a pure 3d 1 electron configuration. Superconductivity at 8 K was observed in the orthorhombic Ti 2 O 3 films. Leveraging the strong structureproperty correlation in transition-metal oxides, our discovery introduces a previously unrecognized route for inducing emergent superconductivity in a newly stabilized polymorph phase in epitaxial thin films.

show abstract

Vacancies and superconductivity in titanium monoxide

Cited by 56 publications

References 2 publications

Superconductivity in Ti4O7 and γ-Ti3O5 films

Superconductivity in Ti4O7 and γ-Ti3O5 films

Electronic Conduction in Oxides

Observation of superconductivity in structure-selected Ti2O3 thin films

Contact Info

Product

Resources

About