Article

Nonlinear Meissner effect in unconventional superconductors

Physical review. B, Condensed matter (Impact Factor: 3.66). 07/1995; 51(22):16233-16253. DOI: 10.1103/PhysRevB.51.16233
Source: arXiv

ABSTRACT We examine the long-wavelength current response in anisotropic superconductors and show how the field-dependence of the Meissner penetration length can be used to detect the structure of the order parameter. Nodes in the excitation gap lead to a nonlinear current-velocity constitutive equation at low temperatures which is distinct for each symmetry class of the order parameter. The effective Meissner penetration length is linear in $H$ and exhibits a characteristic anisotropy for fields in the $ab$-plane that is determined by the positions of the nodes in momentum space. The nonlinear current-velocity relation also leads to an intrinsic magnetic torque for in-plane fields that are not parallel to a nodal or antinodal direction. The torque scales as $H^3$ for $T\rightarrow 0$ and has a characteristic angular dependence. We analyze the effects of thermal excitations, impurity scattering and geometry on the current response of a $d_{x^2-y^2}$ superconductor, and discuss our results in light of recent measurements of the low-temperature penetration length and in-plane magnetization of single-crystals of $YBa_2Cu_3O_{7-\delta}$ and $LuBa_2Cu_3O_{7-\delta}$. Comment: 30 pages, RevTeX file with 16 postscript figures. Submitted to Phys. Rev. B

Download full-text

Full-text

Available from: J. A. Sauls, Jul 07, 2015
0 Followers
 · 
130 Views
  • Source
    • "on the RF field applied in HTS microwave devices, have been reported and the debate still continues [4]. Intrinsic effects such as nonlinear Meissner effects or pair-breaking current can play an important role in the generation of nonlinear characteristics [5]. In addition, the nonlinearities can also be caused by extrinsic effects such as superconductor weak links or Josephson junctions at grain boundaries [6]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The intermodulation distortion (IMD) of a 5-GHz HTS resonator is precisely measured and a nonlinear analysis is conducted. When designing a radio communication system that uses an HTS microwave device, the device's IMD characteristic is one of the most important problems that must be quantitatively evaluated. The amplitudes of third-order IMD (IMD3) and higher-order IMD, which are generated in an HTS resonator given a two-tone fundamental signal, are measured in detail using a fundamental signal cancellation circuit. Moreover, the relative phase of IMD3 is obtained by using a novel measurement system constructed around a reference IMD3 generator. The measured IMD3 phase shows a drastic change in a relatively low IMD3 amplitude region. In addition, the measured resonator exhibits strong higher-order IMD. A nonlinear evaluation using complex power series representation confirms that the drastic phase change may be due to the higher-order distortions present in IMD3.
    IEEE Transactions on Applied Superconductivity 07/2009; DOI:10.1109/TASC.2009.2018459 · 1.32 Impact Factor
  • Source
    • "The combination of nonlinear surface impedance and intermodulation distortion measurements is presently the most powerful probe to discern among different sources of dissipation. Nonlinearities can be roughly classified as having two possible origins: extrinsic, due to the presence of grains and grain boundaries [1], and intrinsic, because of the nonlinear Meissner effect [2], [3]. In the extrinsic case, the Josephson coupling between grains lowers the first vortex penetration field, thus increasing the level of nonlinearities [1], [4]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We present a systematic study of microwave nonlinearity, undertaken on different types of superconductors (Nb, NbN, MgB<sub>2</sub>, Y<sub>1</sub>Ba<sub>2</sub>Cu<sub>3</sub>O<sub>7-delta</sub> ), in thin film form. Experiments are performed in a dielectrically loaded cavity operating at 7 GHz. The dependence of the surface impedance Z<sub>S</sub> and of the third order intermodulation (IMD) products on the power feeding the cavity is analysed, with the aim of shedding a light on the primary mechanisms of nonlinearity. Data from different superconductors are quantitatively compared.
    IEEE Transactions on Applied Superconductivity 07/2007; DOI:10.1109/TASC.2007.900044 · 1.32 Impact Factor
  • Source
    • "These parameters can be related to HTS intrinsic nonlinearities as follows: the nonlinear resistance is due to nonlinearities in quasi-particle conductivity and the nonlinear inductance is due to nonlinearities in penetration depth. At sufficiently small currents , we should expect a quadratic dependence of the overall inductance and resistance per unit length on the total current through the cross section of the TL with (1) with (2) where and are positive to be consistent with the model of intrinsic nonlinearities in HTS TLs [11], [19]. These nonlinear terms just add to the linear , , , and distributed elements of the model of a TL (Fig. 1). "
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper gives closed-form equations for the intermodulation and third harmonic signals generated in a nonlinear transmission line with distributed quadratic nonlinearities in the conductor and dielectric. Although the formulation developed is general, it is intended to be used in planar devices combining high-temperature superconductor (HTS) and oxide ferroelectrics. The analysis in this paper shows that the intermodulation and third harmonic signals produced by an HTS tend to cancel those of a ferroelectric, and that full cancellation is theoretically possible. This opens the way for using HTS/ferroelectric multilayers, not (only) for their tunable or phase-shifting properties, but for highly linear spurious-free planar HTS devices.
    IEEE Transactions on Microwave Theory and Techniques 04/2006; DOI:10.1109/TMTT.2005.864110 · 2.94 Impact Factor