Electrical Transport Properties in 2H-NbS2, -NbSe2, -TaS2 and -TaSe2

Naito, Makio; Tanaka, Shōji

doi:10.1143/jpsj.51.219

Cited by 222 publications

(197 citation statements)

References 16 publications

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“…19 Above T CDW ρ(T)∼aT + b, immediately below T CDW ρ(T)∼dT 2 and at temperatures below about 15-20 K ρ(T)∼cT 5 . The T 5 is due to normal electron-phonon scattering, whereas the T 2 arises due to scattering of electrons by collective excitations of CDW; the rapid drop just below CDW is due to CDW phase ordering.…”

Section: Resultsmentioning

confidence: 95%

“…Just above the superconducting T c interband scattering is negligible and individual s-band and dband normal electron-phonon scattering dominates. 19 The constant term b for such crystals is much smaller than for CDW samples, because disorder suppresses the CDW therefore increases the number of carriers and thus the conductivity.…”

Section: Resultsmentioning

confidence: 99%

“…The constant term b can be attributed to impurity-like carrier scattering of the local CDW fluctuations, and it also appears in dynamical mean field theory (DMFT) of bad metals at high temperature. [19][20][21][22] On very general grounds (Anderson theorem) s-wave superconductivity is immune to weak disorder, 23 on the other hand disorder is detrimental to CDW. We argue that the increase in superconducting T c in the alloy is a direct result of disorder-induced suppression of CDW order.…”

Section: Introductionmentioning

confidence: 99%

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Superconducting order from disorder in 2H-TaSe 2− x S x

Deng

Wang

et al. 2017

npj Quant Mater

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We report on the emergence of robust superconducting order in single crystal alloys of TaSe 2−x S x (0 ≤ × ≤ 2). The critical temperature of the alloy is surprisingly higher than that of the two end compounds TaSe 2 and TaS 2 . The evolution of superconducting critical temperature T c (x) correlates with the full width at half maximum of the Bragg peaks and with the linear term of the high-temperature resistivity. The conductivity of the crystals near the middle of the alloy series is higher or similar than that of either one of the end members 2H-TaSe 2 and/or 2H-TaS 2 . It is known that in these materials superconductivity is in close competition with charge density wave order. We interpret our experimental findings in a picture where disorder tilts this balance in favor of superconductivity by destroying the charge density wave order.npj Quantum Materials (2017) 2:11 ; doi:10.1038/s41535-017-0016-9 INTRODUCTIONThe interplay of disorder and interactions is a fruitful area of investigation. In the absence of electron-electron interactions, disorder can turn a metallic system into an Anderson insulator, 1 but can remain metallic when interactions are important. The additional complexity of competing orders such superconductivity with charge density wave (CDW) or magnetism makes this problem one of the most challenging frontiers in physics. 2-5 A large body of literature is devoted to this interplay in nearly magnetic materials. 6 The interplay of disorder and superconductivity in CDW materials have been less explored than its magnetic analog.Superconductivity and CDW are traditionally viewed as weakcoupling Fermi surface instabilities due to electron-phonon coupling. 7 Arguments have been made both for their cooperation and competition. 8,9 Hexagonal transition metal dichalcogenide 2H-TaSe 2 (P63/mmc space group) undergoes a second-order transition to an incommensurate CDW at 122 K followed by a first-order lock-in transition to a commensurate CDW (CCDW) phase at 90 K, eventually becoming superconducting below 0.14 K upon cooling. 10, 11 2H-TaS 2 has T c = 0.8 K below an in-plane CCDW at 78 K. 10,12 The CDW mechanism in 2H-TaSe 2 involves an electron instability in the bands nested away from the Fermi surface, whereas 2H-TaS 2 features a polar charge and orbital order. 13,14 CDW in 2H-TaSe 2 is dominated by hopping between next-nearest neighbors that creates three weakly coupled triangular sublattices. 15 It is of interest to note that the 2H-TaSe 2 is quasi-twodimensional (2D) metal with pseudogap and with c-axis resistivity 25-50 times higher than the in-plane resistivity, i.e., ρ c (T) >> ρ ab (T). 10,13,[16][17][18] Here, we report that in the 2H-TaSe 2−x S x alloy series the CDW is suppressed and the superconductivity is maximized with

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Superconducting order from disorder in 2H-TaSe 2− x S x

Deng

Wang

et al. 2017

npj Quant Mater

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“…But the conductivity behavior and a transition at 110K in 1T-VSe 2 have similarity to the CDW transition in more covalent polytypes of 2H-variety of NbSe 2 , TaS 2 and TaSe 2 . [1,2,3,4,5] Hence it suggests that in this layered compound 110K -transition is relatively insensitive to the Fermi surface topology and nesting vectors.…”

Section: Introductionmentioning

confidence: 92%

Electronic transport and specific heat of

Yadav

Rastogi

2010

Solid State Communications

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The results of low temperature thermoelectric power and the specific heat of 1T-VSe 2 (Vanadium diselenide) have been reported along with the electrical resistivity, and Hall coefficient of the compound. The Charge Density Wave (CDW) transition is observed near 110K temperature in all these properties. The Thermoelectric power has been measured from 15K to 300K spanning the incommensurate and commensurate CDW regions. We observed a weak anomaly at the CDW transition for the first time in the specific heat of VSe 2 . The linear temperature dependence of resistivity and thermoelectric power at higher temperatures suggests a normal metallic behavior and electron-phonon scattering above the CDW transition. The positive thermoelectric power and negative Hall coefficient along with strongly temperature dependent behavior in the CDW phase suggest a mixed conduction related to the strongly hybridized s-p-d bands in this compound.

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“…[19][20][21] The sign change in NNO can be similarly attributed to the Fermi surface reconstruction associated with the phase transition, leading to the opening of the Mott-Hubbard gap. The emergence of the gap combined with the complex multiband electronic structure of NNO, can result in coexistence of multiple carrier types near T MI .…”

mentioning

confidence: 99%

Field-effect diode based on electron-induced Mott transition in NdNiO₃

et al. 2012

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We studied an electron-induced metal-insulator transition in a two-terminal device based on oxide NdNiO3. In our device, the NdNiO3 is electrostatically doped by the voltage applied between the terminals, resulting in an asymmetric conductivity with respect to the bias polarity. The asymmetry is temperature-dependent and is most significant near the metal-insulator transition. The I-V characteristics exhibit a strong dependence both on the thermal history and the history of the applied voltage bias. Our two-terminal device represents a simple and efficient route for studies of the effect of electron doping on the metal-insulator transition.The ability to electronically control the resistance of materials is the fundamental mechanism underlying the operation of modern semiconductor devices. In addition, a number of advanced materials and structures that exhibit controllable resistance switching phenomena are currently being explored as a basis for the future devices that will combine robust processibility, scalability, energy efficiency, and high speed. In strongly correlated oxide materials exhibiting a metal-insulator transition (MIT), phase transitions between states with different transport and magnetic properties [1-3] provide a fundamental mechanism for the operation of electronic devices with advanced functionalities. Such devices can be controlled by electric field,[4-6] optical excitation, [7] or a combination of thermal and electronic effects. [8,9] The electric field can not only modulate the charge density, but also shift the phase transition temperature, thus enhancing the direct effects of the electric field on the conductivity. The effects of electrical gating on the MIT have been demonstrated in La 0.8 Ca 0.2 MnO 3 films backgated through the substrate, and in NdNiO 3 (NNO) films gated through ionic liquids. [11][12][13][14][15] The electric fieldinduced variations of MIT temperature T MI resulted in a strong variation of the phase-dependent charge density.[17] These experiments provided a significant fundamental insight into the interplay between the charge carrier density and phase transitions in correlated oxides.Studies of electric field effects have so far focused on three-terminal field-effect transistor (FET) structures incorporating a gate electrode separated from the oxide film by an electrically insulating gate dielectric. However, these studies have been constrained by the difficulty of incorporating complex oxides into the standard threeterminal FET structure with a separate gate electrode. Here, we demonstrate a simple unipolar two-terminal device, a field-effect diode (FED), that enables studies of field effects in correlated oxides. The device is more straightforward than a FET both in terms of the fabrication and measurements. In our device geometry, the * Sergei.Urazhdin@emory.edu electric field is determined by the voltage applied between the two terminals. Thus, by measuring the dependence of the device conductivity on the applied voltage, one can determine the effects of the el...

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Electrical Transport Properties in 2H-NbS₂, -NbSe₂, -TaS₂ and -TaSe₂

Cited by 222 publications

References 16 publications

Superconducting order from disorder in 2H-TaSe 2− x S x

Superconducting order from disorder in 2H-TaSe 2− x S x

Electronic transport and specific heat of

Field-effect diode based on electron-induced Mott transition in NdNiO₃

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Electrical Transport Properties in 2H-NbS2, -NbSe2, -TaS2 and -TaSe2

Cited by 222 publications

References 16 publications

Superconducting order from disorder in 2H-TaSe 2− x S x

Superconducting order from disorder in 2H-TaSe 2− x S x

Electronic transport and specific heat of

Field-effect diode based on electron-induced Mott transition in NdNiO3

Contact Info

Product

Resources

About

Electrical Transport Properties in 2H-NbS₂, -NbSe₂, -TaS₂ and -TaSe₂

Field-effect diode based on electron-induced Mott transition in NdNiO₃