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Register a new userMagnetic Field Effects on the Transport Properties of High-Tc Cuprates
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Starting from a recently proposed comprehensive theory for the high-Tc superconductivity in cuprates, we derive a general analytic expression for the planar resistivity, in the presence of an applied external magnetic field $textbf{H}$ and explore its consequences in the different phases of these materials. As an initial probe of our result, we show it compares very well with experimental data for the resistivity of LSCO at different values of the applied field. We also apply our result to Bi2201 and show that the magnetoresistivity in the strange metal phase of this material, exhibits the $H^2$ to $H$ crossover, as we move from the weak to the strong field regime. Yet, despite of that, the magnetoresistivity does not present a quadrature scaling. Remarkably, the resistivity H-field derivative does scale as a function of $frac{H}{T}$, in complete agreement with recent magneto-transport measurements made in the strange metal phase of cuprates cite{Hussey2020}. We, finally, address the issue of the $T$-power-law dependence of the resistivity of overdoped cuprates and compare our results with experimental data for Tl2201. We show that this provides a simple method to determine whether the quantum critical point associated to the pseudogap temperature $T^*(x)$ belongs to the SC dome or not.
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Large pulsed magnetic fields up to 60 Tesla are used to suppress the contribution of superconducting fluctuations (SCF) to the ab-plane conductivity above Tc in a series of YBa2Cu3O6+x single crystals. The fluctuation conductivity is found to vanish nearly exponentially with temperature, allowing us to determine precisely the field Hc(T) and the temperature Tc above which the SCFs are fully suppressed. Tc is always found much smaller than the pseudogap temperature. A careful investigation near optimal doping shows that Tc is higher than the pseudogap T*, which indicates that the pseudogap cannot be assigned to preformed pairs. For nearly optimally doped samples, the fluctuation conductivity can be accounted for by gaussian fluctuations following the Ginzburg-Landau scheme. A phase fluctuation contribution might be invoked for the most underdoped samples in a T range which increases when controlled disorder is introduced by electron irradiation. Quantitative analysis of the fluctuating magnetoconductance allows us to determine the critical field Hc2(0) which is found to be quite similar to Hc(0) and to increase with hole doping. Studies of the incidence of disorder on both Tc and T* enable us to propose a three dimensional phase diagram including a disorder axis, which allows to explain most observations done in other cuprate families.
We show that the resistivity in each phase of the High-Tc cuprates is a special case of a general expression derived from the Kubo formula. We obtain, in particular, the T-linear behavior in the strange metal (SM) and upper pseudogap (PG) phases, the pure $T^2$, Fermi liquid (FL) behavior observed in the strongly overdoped regime as well as the $T^{1+delta}$ behavior that interpolates both in the crossover. We calculate the coefficients: a) of $T$ in the linear regime and show that it is proportional to the PG temperature $T^*(x)$; b) of the $T^2$-term in the FL regime, without adjusting any parameter; and c) of the $T^{1.6}$ term in the crossover regime, all in excellent agreement with the experimental data. From our model, we are able to infer that the resistivity in cuprates is caused by the scattering of holes by excitons, which naturally form as holes are doped into the electron background.
Transport measurements provide important characterizations of the nature of stripe order in the cuprates. Initial studies of systems such as La(1.6-x)Nd(0.4)Sr(x)CuO(4) demonstrated the strong anisotropy between in-plane and c-axis resistivities, but also suggested that stripe order results in a tendency towards insulating behavior within the planes at low temperature. More recent work on La(2-x)Ba(x)CuO(4) with x=1/8 has revealed the occurrence of quasi-two-dimensional superconductivity that onsets with spin-stripe order. The suppression of three-dimensional superconductivity indicates a frustration of the interlayer Josephson coupling, motivating a proposal that superconductivity and stripe order are intertwined in a pair-density-wave state. Complementary characterizations of the low-energy states near the Fermi level are provided by measurements of the Hall and Nernst effects, each revealing intriguing signatures of stripe correlations and ordering. We review and discuss this work.
We have studied the doping dependence of the in-plane and out-of-plane superfluid density, rho^s(0), of two monolayer high-Tc superconductors, HgBa_2CuO_{4+delta} and La_{2-x}Sr_xCuO_4, using the low frequency ac-susceptibility and the muon spin relaxation techniques. For both superconductors, rho^s(0) increases rapidly with doping in the under- and optimally doped regime and becomes nearly doping independent above a critical doping, p_c = 0.20.
In this article, I review progress towards an understanding of the normal state (in-plane) transport properties of high-$T_c$ cuprates in the light of recent developments in both spectroscopic and transport measurement techniques. Against a backdrop of mounting evidence for anisotropic single-particle lifetimes in cuprate superconductors, new results have emerged that advocate similar momentum dependence in the transport decay rate $Gamma$({bf k}). In addition, enhancement of the energy scale (up to the bare bandwidth) over which spectroscopic information on the quasiparticle response can be obtained has led to the discovery of new, unforeseen features that surprisingly, may have a significant bearing on the transport properties at the dc limit. With these two key developments in mind, I consider here whether all the ingredients necessary for a complete phenomenological description of the anomalous normal state transport properties of high-$T_c$ cuprates are now in place.
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