Logarithmic temperature dependence of the resistivity of Nd2−xCexCuO4−y

We consider effects of Coulomb interaction in a granular normal metal at not very low temperatures suppressing weak localization effects. In this limit calculations with the initial electron Hamiltonian are reduced to integrations over a phase variable with an effective action, which can be considered as a bosonization for the granular metal. Conditions of the applicability of the effective action are considered in detail and importance of winding numbers for the phase variables is emphasized. Explicit calculations are carried out for the conductivity and the tunneling density of states in the limits of large g ≫ 1 and small g ≪ 1 tunnelling conductances. It is demonstrated for any dimension of the array of the grains that at small g the conductivity and the tunnelling density of states decay with temperature exponentially. At large g the conductivity also decays with decreasing the temparature and its temperature dependence is logarithmic independent of dimensionality and presence of a magnetic field. The tunnelling density of states for g ≫ 1 is anomalous in any dimension but the anomaly is stronger than logarithmic in low dimensions and is similar to that for disordered systems. The formulae derived are compared with existing experiments. The logarithmic behavior of the conductivity at large g obtained in our model can explain numerous experiments on systems with a granular structure including some high T c materials.

show abstract

“…It was also observed in phase compounds of Nd 2−x Ce x CuO 4−y , Ref. 38 . In each case the reason for such a behavior was not clear.…”

Section: Discussionmentioning

confidence: 70%

Coulomb effects in granular materials at not very low temperatures

2003

View full text Add to dashboard Cite

show abstract

“…1 This behavior has been reported for several granular metallic systems. 11,12 As can be seen in Fig. 2͑b͒, some of the nanocrystalline samples show a logarithmic temperature dependence at low temperatures, clearly indicating a metallic behavior in the granular limit g Ӷ g 0 .…”

mentioning

confidence: 83%

Low-temperature transport in highly boron-doped nanocrystalline diamond

et al. 2009

View full text Add to dashboard Cite

We studied the transport properties of highly boron-doped nanocrystalline diamond thin films at temperatures down to 50 mK. The system undergoes a doping-induced metal-insulator transition with an interplay between intergranular conductance g and intragranular conductance g 0 , as expected for a granular system. The conduction mechanism in the case of the low-conductivity films close to the metal-insulator transition has a temperature dependence similar to Efros-Shklovskii type of hopping. On the metallic side of the transition, in the normal state, a logarithmic temperature dependence of the conductivity is observed, as expected for a metallic granular system. Metallic samples far away from the transition show similarities to heavily borondoped single-crystal diamond. Close to the transition, the behavior is richer. Global phase coherence leads in both cases to superconductivity ͑also checked by ac susceptibility͒, but a peak in the low-temperature magnetoresistance measurements occurs for samples close to the transition. Corrections to the conductance according to superconducting fluctuations account for this negative magnetoresistance.

show abstract

“…The nature of the metallic state that emerges upon doping the insulating parent compounds has remained a central open question. Moreover, below a compound specific doping level, the low-temperature resistivity for both types of cuprates develops a logarithmic upturn that appears to be related to disorder, yet whose microscopic origin has remained unknown [1,[5][6][7]. In contrast, at high dopant concentrations, the cuprates are good metals with welldefined Fermi surfaces and clear evidence for Fermi-liquid (FL) behavior [8][9][10][11][12][13][14].…”

mentioning

confidence: 99%

Hidden Fermi-liquid Charge Transport in the Antiferromagnetic Phase of the Electron-Doped Cuprate Superconductors

Tabiś

et al. 2016

Phys. Rev. Lett.

View full text Add to dashboard Cite

Systematic analysis of the planar resistivity, Hall effect and cotangent of the Hall angle for the electron-doped cuprates reveals underlying Fermi-liquid behavior even deep in the antiferromagnetic part of the phase diagram. The transport scattering rate exhibits a quadratic temperature dependence, and is nearly independent of doping, compound and carrier type (electrons vs. holes), and hence universal. Our analysis moreover indicates that the material-specific resistivity upturn at low temperatures and low doping has the same origin in both electron-and hole-doped cuprates.The cuprates feature a complex phase diagram that is asymmetric upon electron-versus hole-doping [1] and plagued by compound-specific features associated with different types of disorder and crystal structures [2], often rendering it difficult to discern universal from nonuniversal properties. What is known for certain is that the parent compounds are antiferromagnetic (AF) insulators, that AF correlations are more robust against doping with electrons than with holes [3,4], and that pseudogap (PG) phenomena, seemingly unusual charge transport behavior, and d-wave superconductivity appear upon doping the quintessential CuO 2 planes [1]. The nature of the metallic state that emerges upon doping the insulating parent compounds has remained a central open question. Moreover, below a compound specific doping level, the low-temperature resistivity for both types of cuprates develops a logarithmic upturn that appears to be related to disorder, yet whose microscopic origin has remained unknown [1,[5][6][7]. In contrast, at high dopant concentrations, the cuprates are good metals with welldefined Fermi surfaces and clear evidence for Fermi-liquid (FL) behavior [8][9][10][11][12][13][14].In a new development, the hole-doped cuprates were found to exhibit FL properties in an extended temperature range below the characteristic temperature T * * (T * * < T * ; T * is the PG temperature): (i) the resistivity per CuO 2 sheet exhibits a universal, quadratic temperature dependence, and is inversely proportional to the doped carrier density p, ρ ∝ T 2 /p [15]; (ii) Kohler's rule for the magnetoresistvity, the characteristic of a conventional metal with a single relaxation rate, is obeyed, with a Fermi-liquid scattering rate, 1/τ ∝ T 2 [16]; (iii) the optical scattering rate exhibits the quadratic frequency dependence and the temperature-frequency scaling expected for a Fermi liquid [17]. In this part of the phase diagram, the Hall coefficient is known to be approximately independent of temperature and to take on a value that corresponds to p, R H ∝ 1/p [18]. In order to explore the possible connection among the different regions of the phase diagram, an important quantity to consider is the cotangent of the Hall angle, cot(θ H ) = ρ/(HR H ). For simple metals, this quantity is proportional to the transport scattering rate, cot(θ H ) ∝ m * /τ (H the magnetic field, and m * the effective mass). It has long been known that cot(θ H ) ∝ T 2 in the "strange-metal" ...

show abstract

Logarithmic temperature dependence of the resistivity of Nd2−xCexCuO4−y

Cited by 17 publications

References 3 publications

Coulomb effects in granular materials at not very low temperatures

Coulomb effects in granular materials at not very low temperatures

Low-temperature transport in highly boron-doped nanocrystalline diamond

Hidden Fermi-liquid Charge Transport in the Antiferromagnetic Phase of the Electron-Doped Cuprate Superconductors

Contact Info

Product

Resources

About