Showing papers on "High-temperature superconductivity published in 1998"
TL;DR: In this paper, the authors link the physics of the superconductor-insulator transition in thin films to other systems believed to exhibit quantum phase transitions, such as high temperature superconductors, Josephson junction arrays, two-dimensional electron gases and various spin systems.
Abstract: The investigation of superconductivity in the presence of disorder began 60 years ago with the work of Alexander Shal'nikov at the Institute for Physical Problems in Moscow. The subject has played an ongoing role in condensed matter physics over the years. Interest has recently been heightened by the possibility that the disorder‐driven or magnetic‐field‐driven quenching of superconductivity in systems at the limit of zero temperature and two dimensions might be quantum phase transitions. That would link the physics of the superconductor‐insulator transition in thin films to other systems believed to exhibit quantum phase transitions—for example, helium‐4 in porous media, high temperature superconductors, Josephson‐junction arrays, two‐dimensional electron gases and various spin systems.
276 citations
TL;DR: In this paper, two-dimensional neutron-scattering imaging of YBa2Cu3O6.6 was presented, which revealed that the low-frequency magnetic excitations are virtually identical to those of similarly doped La2−xSrxCuO4.
Abstract: An important feature of the high-transition-temperature (high-Tc) copper oxide superconductors is the magnetism that results from the spins associated with the incomplete outer electronic shells (3d9) of the copper ions. Fluctuations of these spins give rise to magnetic excitations of the material, and might mediate the electron pairing that leads to superconductivity. If the mechanism for high-Tc superconductivity is the same for all copper oxide systems, their spin fluctuations should be universal. But so far, theopposite has seemed to be the case: neutron scattering data reveal clear differences between the spin fluctuations for two major classes of high-Tc materials, La2−xSrxCuO4 (1-3) and YBa2Cu3O7−x (4-6), whose respective building blocks are CuO2 layers and bilayers. Here we report two-dimensional neutron-scattering imaging of YBa2Cu3O6.6, which reveals that the low-frequency magnetic excitations are virtually identical to those of similarly doped La2−xSrxCuO4. Thus, the high-temperature (Tc ≲ 92 K) superconductivity of the former materials may be related to spatially coherent low-frequency spin excitations that were previously thought to be unique to the lower-Tc (<40 K) single-layer La2−xSrxCuO4 family.
211 citations
TL;DR: In this paper, a theoretical analysis in terms of an extended Lindemann criterion provides a quantitative description of the resulting vortex-matter phase boundaries and the behavior of the transition lines with varying anisotropy and disorder.
Abstract: The vortex-matter in superconductors is generally believed to exist in two main phases, vortex-solid and vortex-liquid. Recent investigations of the phase diagram of anisotropic high-temperature superconductors indicate, however, the existence of at least three distinct phases: relatively ordered quasi-lattice, highly-disordered entangled vortex-solid, and a liquid phase. A theoretical analysis in terms of an extended Lindemann criterion provides a quantitative description of the resulting vortex-matter phase boundaries and the behavior of the transition lines with varying anisotropy and disorder.
152 citations
TL;DR: In this article, a model based on universal properties of high-Tc superconductors only is presented for the transport characteristics of grain boundaries in these materials, which accounts for the superconducting as well as for the normal-state transport properties observed in a comprehensive study of YBa2Cu3O7−δ [001]-tilt bicrystalline grain boundaries with varying misorientation angles and of two different symmetries.
Abstract: A model, based on universal properties of high-Tc superconductors only, is presented for the transport characteristics of grain boundaries in these materials The model accounts for the superconducting as well as for the normal-state transport properties observed in a comprehensive study of YBa2Cu3O7−δ [001]-tilt bicrystalline grain boundaries with varying misorientation angles and of two different symmetries
131 citations
TL;DR: The interlayer pair tunneling energy (similar to the Josephson or Lawrence-Doniach energy) is the motivation for superconductivity and is satisfied for all dopings in (La,Sr)2 CuO4 and also in optimally doped Hg(Ba)2CuO5, which was measured recently, but seems to be strongly violated in measurements on single crystals of Tl2Ba2CuOs.
Abstract: In the interlayer theory of high-temperature superconductivity, the interlayer pair tunneling energy (similar to the Josephson or Lawrence-Doniach energy) is the motivation for superconductivity. This connection requires two experimentally verifiable identities: the coherent normal-state conductance must be smaller than the “Josephson” coupling energy, and the Josephson coupling energy must be equal to the condensation energy of the superconductor. The first condition is well satisfied in the only case that is relevant, (La,Sr)2CuO4, but the second condition has been questioned. It is satisfied for all dopings in (La,Sr)2CuO4 and also in optimally doped Hg(Ba)2CuO5, which was measured recently, but seems to be strongly violated in measurements on single crystals of Tl2Ba2CuO6.
105 citations
TL;DR: In this article, a microscopic model for the condensation energy of high-T c superconductors is proposed, which is based on the t -J model. But the model is not suitable for high-transition-temperature superconductivity and it cannot capture the interplay between the electrons' kinetic energy and their antiferromagnetic exchange interaction.
Abstract: One of the main challenges to theoretical attempts to understand the microscopic mechanism of high-transition-temperature (high- T c) superconductivity is to account quantitatively for the superconducting condensation energy, the energy by which the normal state differs from the superconducting state1,2,3,4,5,6. A microscopic model commonly used to describe the superconducting copper oxides, the t - J model7, is thought to capture the essential physics of the phenomenon: the interplay between the electrons' kinetic energy and their antiferromagnetic exchange interaction. Within the t - J model the condensation energy can be related to the change in the dynamical spin structure between the superconducting and the normal states8. Here we propose a microscopic mechanism for the condensation energy of high- T c superconductors. Within this mechanism, the appearance of a resonance in the superconducting state9,10,11,12,13 enables the antiferromagnetic exchange energy in this state to be lowered relative to the normal state. We show that the intensity of the resonant neutron-scattering peak observed previously in YBa2Cu3O7 when it undergoes the transition to the superconducting state14,15,16 is in quantitative agreement with the condensation energy of these materials2,3.
95 citations
TL;DR: In this article, the flux pinning characteristics of ternary melt-processed (Nd033Eu033Gd033)Ba2Cu3Oy (NEG) superconductors are studied in the temperature range 60⩽T ⩽90 K NEG samples exhibit a strongly developed peak effect in the dependence of the critical current densities on the external field, Ha.
Abstract: The flux pinning characteristics of ternary melt-processed (Nd033Eu033Gd033)Ba2Cu3Oy (NEG) superconductors are studied in the temperature range 60⩽T⩽90 K NEG samples exhibit a strongly developed peak effect in the dependence of the critical current densities on the external field, Ha The scaling of the pinning forces versus the reduced field h=Ha/Hirr (where Hirr denotes the irreversibility field) yields a peak at h0=05 which is an indication of pinning provided by a spatial variation of the transition temperature The presence of a weaker superconducting second phase is demonstrated by means of field cooling and warming experiments in fields up to 7 T Furthermore, we discuss the possible effect of the magnetic moments of Gd and Nd on the flux pinning
72 citations
TL;DR: The current status of basic research on the high-temperature cuprate superconductors and the prospects for technological applications of these materials are discussed in this article, along with recent developments concerning other novel supercondors are also briefly described.
70 citations
TL;DR: In this article, a review of the effects of vortex-lattice melting, flux pinning, flux creep and critical current density on superconducting materials is presented, and a number of consequences are discussed.
Abstract: The electrodynamic behaviour of the high-temperature cuprate superconductors is strongly affected by the anisotropy of these layered materials. Their transport, magnetic and pinning properties are determined by the properties of vortices, which can be regarded as stacks of two-dimensional (2D) pancake vortices (with cores localized in the layers, bilayers or trilayers) connected by Josephson vortices (with cores localized in the nonsuperconducting charge-reservoir layers). When the Josephson coupling between the superconducting layers is strong, as in YBCO, the line energy associated with the Josephson vortices is large, the 2D pancake vortices in adjacent layers are strongly coupled and the magnetic anisotropy of the superconductor is relatively weak. When the Josephson coupling is weak, as in BSCCO, the line energy associated with the Josephson vortices is small, the 2D pancake vortices in adjacent layers are weakly coupled and the magnetic properties are highly anisotropic and nearly 2D. The transport properties for currents flowing parallel to the layers are dominated by 2D pancake vortex motion, while those for currents flowing perpendicular to the layers are dominated by Josephson vortex motion. In this paper, I review these effects and discuss a number of consequences for vortex-lattice melting, flux pinning, flux creep and the critical current density.
58 citations
TL;DR: In this article, the authors consider the implications of grain boundaries on the electronic band structures of high-Tc cuprates and show that the normal state properties observed may be caused by depletion layers formed at the interfaces.
Abstract: The normal state transport properties of grain boundaries in high-Tc superconductors, of central importance for a large number of electronic applications, still lack a thorough explanation In this contribution we consider the implications of grain boundaries on the electronic band structures of high-Tc cuprates It is shown that the normal state properties observed may be caused by depletion layers formed at the interfaces
TL;DR: In this article, the Andreev bound states at the surface of superconductors are observed for any pair potential showing a sign change in different k-directions with their spectral weight depending on the relative orientation of the surface and the pair potential.
Abstract: Andreev bound states at the surface of superconductors are expected for any pair potential showing a sign change in different k-directions with their spectral weight depending on the relative orientation of the surface and the pair potential. We report on the observation of Andreev bound states in high temperature superconductors (HTS) employing tunneling spectroscopy on bicrystal grain boundary Josephson junctions (GBJs). The tunneling spectra were studied as a function of temperature and applied magnetic field. The tunneling spectra of GBJ formed by YBa2Cu3O
(YBCO), Bi2Sr2CaCu2O
(BSCCO), and La1.85Sr0.15CuO4 (LSCO) show a pronounced zero bias conductance peak that can be interpreted in terms of Andreev bound states at zero energy that are expected at the surface of HTS having a d-wave symmetry of the order parameter. In contrast, for the most likely s-wave HTS Nd1.85Ce0.15CuO4-y (NCCO) no zero bias conductance peak was observed. Applying a magnetic field results in a shift of spectral weight from zero to finite energy. This shift is found to depend nonlinearly on the applied magnetic field. Further consequences of the Andreev bound states are discussed and experimental evidence for anomalous Meissner currents is presented.
TL;DR: In this paper, the intrinsic limiting behavior of a perfect superconducting thin film was discussed and the present status of the present state of the super-conducting filters was discussed, and it was shown that increases in resonator Q to ∼106 and decreases in intermodulation by a factor of ∼104, compared with today's values, might be achieved.
Abstract: Cuprate superconducting thin films are being used to make compact low power microwave devices. In recent years, with improved materials and designs, there has been a steady improvement in device performance, notably an increase in resonator Q and a decrease in the nonlinear intermodulation. It is important to understand how much improvement can be expected. Here we discuss the intrinsic limiting behavior that one might achieve with a perfect film, review the present status, and discuss what the limiting behavior implies for high temperature superconducting filters. Our analysis indicates that increases in unloaded Q to ∼106 and decreases in intermodulation by a factor of ∼104, compared with today’s values, might be achieved.
Book•
30 Jun 1998
TL;DR: In this article, the authors discuss the effect of impurity atoms on the performance of Ionic diffusion in Ionic materials and propose a method to remove impurity from Ionic structures.
Abstract: POINT DEFECTS The Important Defects Point Defects The Equilibrium Concentration of Schottky Defects in Crystals The Equilibrium Concentration of Frenkel Defects in Crystals Schottky and Frenkel Defects in Crystals Schottky and Frenkel Defects: Trends and Further Considerations Case Study: The Photographic Process Supplementary Reading ATOMIC MOBILITY: DIFFUSION Introduction Self-Diffusion and Tracer Diffusion Chemical Diffusion Chemical Diffusion, Intrinsic Diffusion, and Self-Diffusion Diffusion in Ionic Crystals Case Study: Corrosion and Oxidation Reactions Short-Circuit Diffusion THE ATOMIC THEORY OF DIFFUSION Introduction Self-Diffusion Mechanisms The Arrhenius Equation and the Effect of Temperature The Relationship between D and Diffusion Distance Correlation Effects Case History: Integrated Circuits Ionic Conductivity NON-STOICHIOMETRY AND POINT DEFECTS The Composition of Solids Solid Solutions Case Study: Magnetic Spinels Non-Stoichiometry Substitutional Impurities Density and Defect Type Interpolation Defect Chemistry Point Defect Interactions FAST ION CONDUCTORS Introduction The Lithium Iodide Battery Disordered Cation Compounds Calcia-Stabilized Zirconia and Related Fast Qxygen Ion Conductors Case Study: Fuel Cells The B-Alumina Oxides The LixTiS3N Battery: Role Reversal NON-STOICHIOMETRY AND ELECTRONIC CONDUCTION Introduction Non-stoichiometry in Pure Oxides The Effect of Impurity Atoms Electronic Conduction in Ionic Materials Thermoelectric Effects Band Theory Band Conduction and Hoping Conduction Case Study: Turning an Insulator into a Metal DEFECTS AND OPTICAL PROPERTIES Colour Case Study: Rubies and Ruby Lasers Transparent Electrodes Electrochromic Films Case Study: The Structure of the F-Centre Electron and Hole Centres Case Study: The Search for a Colour Centre Based Information Storage Medium Colour Centre Lasers DEFECTS, COMPOSITION RANGES AND CONDUCTIVITY The Equilibrium Partial Pressure of Oxygen Over an Oxide Variation of Partial Pressure with Composition Electronic Conductivity and Partial Pressure for Ni-xO Case Study: Co1-xO Electronic Conductivity and Partial Pressure for Zn1+xO Brouwer Diagrams Case Study: An Experimentally Determined Brouwer Diagram CdTe POINT DEFECTS AND PLANAR DEFECTS Point Defects in Nearly Stoichiometric Crystals Point Defect Clusters Microdomains Point Defect Ordering and Assimilation Inerpolation Planar Faults and Boundaries Crystallorgraphic Shear Phases Chemical Twinning Planar Intergrowths Case Study: The Nb2O5 Block Structures Pentagonal Column Phases Defect-Free Structures: Modulated and Incommensurate Phases DEFECTS AND NON-STOICHIOMETRY IN HIGH TEMPERATURE SUPERCONDUCTORS Superconductivity and Superconductors High Temperature Oxide Superconductors Superconducting Oxides Which do not Contain Copper High-Temperature Superconducting Copper Oxides La2CuO4 Electron Superconductors YB2Cu3O7 and Related Phases Pb2Sr2Ycu3O8 The Bi, TI,. And Hg Homologous Series of Superconductors Conclusions NON-STOICHIOMETRY: AN OVERVIEW Ordering, Assimilation, and Elimination of Defects Thermodynamics and Structures Theories and Calculations Defect Structures and Configurations Surface and Interfaces Molecular Dynamics
TL;DR: In this paper, proximity effect coupling in superconducting-antiferromagnetic-superconducting sandwiches using the recently developed $\mathrm{SO}(5)$ effective theory of high temperature superconductivity was considered.
Abstract: We consider proximity effect coupling in superconducting-antiferromagnetic-superconducting sandwiches using the recently developed $\mathrm{SO}(5)$ effective theory of high temperature superconductivity. We find that, for narrow junctions, the $A$ region acts like a strong superconductor, and that there is a critical junction thickness which depends on the effective $\mathrm{SO}(5)$ coupling constants and on the phase difference across the junction, at which the $A$ region undergoes a Freedericksz-like transition to a state which is intermediate between superconductor and antiferromagnet. For thick junctions, the current-phase relation is sinusoidal, as in standard SNS and SIS junctions, but for thin junctions it shows a sharp break in slope at the Freedericksz point.
TL;DR: In this paper, a spin polarized current was injected into high Tc superconductors, resulting in a significant reduction in the superconductor's critical current, which may serve as the basis of a new class of superconducting devices for control, switching and amplification.
Abstract: A spin polarized current has been injected into high Tc superconductors resulting in a significant reduction in the superconductor’s critical current. Such injection may serve as the basis of a new class of superconducting devices for control, switching and amplification. Preliminary results using both Permalloy and CMR materials as injectors are presented.
TL;DR: In this paper, the effect of the superconducting gap nodes on the vortex lattice properties of high temperature superconductors at very low temperatures was studied and the nonlinear, nonlocal and nonanalytic nature of this effect was shown to have measurable consequences for the vortex geometry and the effective penetration depth in the mixed state.
Abstract: We study the effect of the superconducting gap nodes on the vortex lattice properties of high temperature superconductors at very low temperatures. The nonlinear, nonlocal and nonanalytic nature of this effect is shown to have measurable consequences for the vortex lattice geometry and the effective penetration depth in the mixed state as measured by muon-spin-rotation experiments.
TL;DR: In this article, the authors describe a calorimetric setup for ac loss measurements on long length high-temperature superconductors carrying ac transport currents in ac external magnetic fields at variable temperatures.
Abstract: The use of high-temperature superconductors in electric power components requires the knowledge of their alternating current (ac) losses. Methods are therefore needed to characterize the conductors with respect to their ac losses under applicationlike conditions. In this article we describe a calorimetric setup for ac loss measurements on long length high-temperature superconductors carrying ac transport currents in ac external magnetic fields at variable temperatures. The variable temperature is achieved by a thermal connection between the sample and a cooling machine. Current in copper coils generates the magnetic field parallel to the plane of the tape and perpendicular to the transport current. This current can be induced in the coil-formed sample. Two slightly different methods are used to determine the ac losses, one in which the temperature rise of the sample, caused by the ac losses, is compared to the temperature rise caused by a reference heater and another in which the increase in power dissipa...
TL;DR: In this paper, the current status of basic research on the high temperature cuprate superconductors and prospects for technological applications of these materials are discussed, and recent developments concerning other novel supercondors are also briefly described.
Abstract: The current status of basic research on the high temperature cuprate superconductors and prospects for technological applications of these materials is discussed. Recent developments concerning other novel superconductors are also briefly described.
TL;DR: In this paper, the electronic properties of cuprate superconductors have been studied by measuring the reflectance over the frequency range from the far-infrared to the near-ultraviolet (roughly, 10 meV-5 eV).
Abstract: The electronic properties of the cuprate superconductors have been studied by measuring the reflectance over the frequency range from the far-infrared to the near-ultraviolet(roughly, 10 meV-5 eV). There is an interesting behavior in both the normal state and the superconducting state. In the normal state, there is the well-known non-Drude distribution of the doping-induced spectral weight. In the superconducting state, the spectral weight of the superconducting condensate correlates with Tc in a variety of materials. Remarkably, in optimally doped superconductors, only about 20% of the doping-induced carriers joins the superfluid; the rest of the spectral weight remains at finite frequencies.
TL;DR: Theoretical and experimental results for a series of 100, 300, 500 and 1000 W HTS motors with cylindrical and disk rotors are presented in this paper, where it is shown that, at liquid nitrogen temperatures, the specific mass-dimension parameter of hysteresis HTS machines is 5-7 times better than for the conventional hystresis machines.
Abstract: New types of electrical motors based on bulk high temperature superconductors (HTS) are presented. Theoretical and experimental research of these motors is described. Results for a series of 100, 300, 500 and 1000 W HTS motors with cylindrical and disk rotors are presented. It is shown that, at liquid nitrogen temperatures, the specific mass-dimension parameter of hysteresis HTS machines is 5–7 times better than for the conventional hysteresis machines.
TL;DR: In this article, the use of superconductors as permanent magnets is discussed, and a summary of the forces and torques available is given, as well as ways of obtaining maximum repulsion and attraction without demagnetizing the sample.
Abstract: A summary is given of the various techniques used to prepare melt processed YBCO. The use of these materials as permanent magnets is discussed. Since nearly all applications involve demagnetizing fields of some kind, these are compared with the equivalent ferromagnetic material. Superconductors behave in the opposite way to ferromagnets in that a reversed field can increase the magnetization, while a field parallel to the magnetization quickly reduces it to zero. Then ways of obtaining maximum repulsion and attraction without demagnetizing the sample are described. A summary of the forces and torques available is given. In particular, it is shown that YBCO can provide extremely high current densities in rotating machines.
TL;DR: The existing wide spread knowhow about dielectric performance in helium cooled transmission lines which were already developed up to a prototype stage can be used with benefit for the design of liquid nitrogen cooled lines as mentioned in this paper.
TL;DR: In this paper, the irreversibility lines in superconductors containing various amounts (0.3-0.7 wt%) of uranium and various amounts of the fissionable isotope were investigated.
Abstract: Results on the enhancement of critical current densities in melt-textured bulk (Y-123) superconductors, which were doped with and exposed to thermal neutron irradiation to create fission tracks, are presented. These tracks, which all originate from U-containing clusters of a stable UPtYBaO compound, form isotropic `starlike' defects with diameters of approximately 10 nm and lengths of . However, if we consider projections onto the symmetry plane of the flux line lattice and allow for a certain tilt modulus , their pinning-effective size is mostly (90%) between 10 and 20 nm, i.e. only twice as large as the characteristic defect structure (amorphous collision cascades with diameters of nm) introduced into undoped superconductors by fast neutron irradiation. We report on studies of and the irreversibility lines in superconductors containing various amounts (0.3-0.7 wt%) of uranium and various amounts of the fissionable isotope . In the best case (0.3 wt% U, thermal neutrons), we find (77 K) to be around (0 T) and (5 T). Control experiments on samples containing (nominally) only and exposure to thermal or to thermal plus fast neutrons confirm the above flux pinning considerations. As reported before for undoped melt-textured Y-123, the irreversibility lines remain practically unchanged due to the presence of strongly pinning Y-211 precipitates.
TL;DR: The magnetisation curves M (H, T ) of the most anisotropic high temperature superconductors cross in a single point M * (T * ), independently of the magnetic field H that is applied perpendicular to the superconducting planes as discussed by the authors.
Abstract: The magnetisation curves M ( H , T ) of the most anisotropic high temperature superconductors cross in a single point M * ( T * ), independently of the magnetic field H that is applied perpendicular to the superconducting planes. This property may be very generally derived from the singular part of the free energy of a two-dimensional (2D) superconductor with fluctuations at T c . Correspondingly, three-dimensional (3D) superconductors have a crossing point in the quantity M / H 1/2 at T c , with an amplitude proportional to the anisotropy ratio γ ≡( m c / m ab ) 1/2 .
TL;DR: In this article, the melting and solidification behavior of high-temperature superconductors based on BSSCO is studied on the basis of the resultant microstructure and its relation to the critical currents obtained.
Abstract: High-temperature superconductors based on BSSCO are interesting for applications in current lead systems required for superconducting magnets working at cryogenic temperatures as well as to facilitate the development of cryocooled turnkey units. The two BSCCO phases considered for applications at or below 77 K, the 110 K 2223 and the 90 K 2212, differ substantially in processing conditions. Some of these differences are presented and discussed in this paper, especially in connection with melt processing methods. Results obtained with the preparation of these phases using the laser float zone melting method are presented in order to analyse some of the most important differences between 2223 and 2212. Their melting and solidification behaviour is studied on the basis of the resultant microstructure and its relation to the critical currents obtained. The 2212 phase is shown to exhibit improved properties and processing conditions that make it more interesting from the fabrication point of view and for the applications considered here.
TL;DR: In this paper, a self-consistent scheme was proposed to extract the demagnetization factor of the transport critical current (Jc) from the Jc(H0) data itself.
Abstract: The transport critical current Jc in a polycrystalline superconductor is a hysteretic function of applied magnetic field H0 due to flux trapping by grains. This effect has been observed by several groups and attempts have been made to calculate the intergranular field Hi as a function of the applied H0 in terms of an effective geometrical demagnetization factor D. In general a first-principles calculation of D is very difficult, and furthermore, D is not constant but is itself a hysteretic function of H0. We develop a self-consistent scheme to extract the D and Hi directly from the Jc(H0) data itself. Our model exploits the fact that there are two field ranges for which the demagnetizing field is a simple function of H0. At low virgin fields, in the Meissner state, the susceptibility χv≈−1/4π is well defined, leading to a multiplicative correction: Hi=H0/(1+D4πχv). For fields that have returned from high values, a complete critical state is established and M is well defined—although χv is unknown. This le...
Book•
30 Nov 1998
TL;DR: A survey of superconducting cuprates can be found in this paper, where the authors discuss the properties of high-tc superconductors and their applications in magnet and energy applications.
Abstract: Preface. 1. Introduction. 2. The Superconducting State. 3. A Survey of Superconducting Cuprates. 4. Physical Properties of High-Tc Superconductors. 5. Processing of Superconducting Powders. 6. Conductor Fabrication. 7. Foundations of Applied Superconductivity. 8. Magnet and Energy Applications. 9. Outlook. References. Subject Index.
TL;DR: In this article, the stability of a Bi-2223/Ag multifilamentary composite conductor against fast transport current ramps was studied by using a numerical model based on the two-dimensional magnetic diffusion and heat conduction equations.
Abstract: Stability of a Bi-2223/Ag multifilamentary composite conductor against fast transport current ramps was studied by using a numerical model. The model was based on the two-dimensional magnetic diffusion and heat conduction equations. Calculations were carried out both in an adiabatic mode and pool boiling modes in liquid helium, hydrogen and nitrogen. When estimating the heat load (AC losses), real temperature dependent current density–electric field characteristics were used. The results computed by the finite element method are presented and discussed with special emphasis on differences of the stability considerations between high-temperature and low-temperature superconductors.