Non-logarithmic magnetic relaxation in Bi2.2Sr1.7CaCu2O8 single crystals; evidence for collective flux pinning

Svedlindh, Peter; Rossel, C.; Niskanen, K.; Norling, P.; Nordblad, Per; Lundgren, L.; Chandrashekhar, G. V.

doi:10.1016/0921-4534(91)90036-x

Cited by 45 publications

(7 citation statements)

References 30 publications

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“…Typical experimental values for the activation energy U, are of the order of 10 -10 K Maley et a/. , 1990;Zavaritsky, 1992 First, the decay rate S decreases with increasing time, producing an upward curvature in a plot of the logarithmic time decay of the diamagnetic current (Svedlindh et a/. , 1991.…”

Section: Classical Creepmentioning

confidence: 99%

“…On the experimental side, such novel phenomena include the broadening of the resistive transition in a finite magnetic field (Eye et a/. , 1988;Palstra et al , 1988b;Tinkham, 1988a), the existence of a distinct irreversibility line far below H, (Miiller, Takashige, and 2 Bednorz, 1987), which often is associated with a melting or glass transition (Koch, Foglietti, and Fisher, 1990;Farrell, Rice, and Ginsberg, 1991), the presence of giant creep Yeshurun et al , 1989) even at temperatures far below T"manifesting itself in a fast magnetic relaxation which furthermore proceeds nonlinearly in the time logarithm (Svedlindh et al , 1991;Thompson, Sun, and Holtzberg, 1991), a rapid decrease in the critical current density j, with increasing temperature even far below the superconducting transition (Senoussi et al , 1988), and the appearance of quantum effects on approaching zero temperature Lensink et al , 1989;Fruchter et al , 1991).…”

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confidence: 97%

“…As a result the actual value for t, is much bigger than the microscopic time ( -10 " s) used in the analysis of the early relaxation experiments on giant fiux creepMalozemoff and Fisher, 1990). In fact, more recent experiments(Konczykowski, MalozemoA;Svedlindh et al , 1991;Zavaritsky and Zavaritsky, 1991; Brawner, Ong, and Wang, 1993) produce much larger values for the time scale t, , of the order of -10 -1 s. This compares well with the theoretical estimate [see Eq. (10.33) and use u.…”

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confidence: 97%

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Vortices in high-temperature superconductors

et al. 1994

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With the high-temperature superconductors a qualitatively new regime in the phenomenology of type-II superconductivity can be accessed. The key elements governing the statistical mechanics and the dynamics of the vortex system are (dynamic) thermal and quantum fluctuations and (static) quenched disorder. The importance of these three sources of disorder can be quantified by the Ginzburg number Gi =(T, /H, sg ) /2, the quantum resistance Qu =(e /A'i(p"/ski, and the critical current-density ratio j,/jo, with j, and jo denoting the depinning and depairing current densities, respectively (p" is the normal-state resistivity and E = m /M (1 denotes the anisotropy parameter). The material parameters of the oxides conspire to produce a large Ginzburg number Gi -10 and a large quantum resistance Qu -10 ', values which are by orders of magnitude larger than in conventional superconductors, leading to interesting effects such as the melting of the vortex lattice, the creation of new vortex-liquid phases, and the appearance of macroscopic quantum phenomena. Introducing quenched disorder into the system turns the Abrikosov lattice into a vortex glass, whereas the vortex liquid remains a liquid. The terms "glass" and "liquid" are defined in a dynamic sense, with a sublinear response p=BE/Bji c characterizing the truly superconducting vortex glass and a finite resistivity p( j~0))0 being the signature of the liquid phase. The smallness of j,/jo allows one to discuss the influence of quenched disorder in terms of the weak collective pinning theory. Supplementing the traditional theory of weak collective pinning to take into account thermal and quantum fluctuations, as well as the new scaling concepts for elastic media subject to a random potential, this modern version of the weak collective pinning theory consistently accounts for a large number of novel phenomena, such as the broad resistive transition, thermally assisted flux flow, giant and quantum creep, and the glassiness of the solid state. The strong layering of the oxides introduces additional new features into the thermodynamic phase diagram, such as a layer decoupling transition, and modifies the mechanism of pinning and creep in various ways. The presence of strong (correlated) disorder in the form of twin boundaries or columnar defects not only is technologically relevant but also provides the framework for the physical realization of novel thermodynamic phases such as the Bose glass. On a macroscopic scale the vortex system exhibits self-organized criticality, with both the spatial and the temporal scale accessible to experimental investigations.

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Section: Classical Creepmentioning

confidence: 99%

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confidence: 97%

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confidence: 97%

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Vortices in high-temperature superconductors

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“…Flux creep is a phenomenon which may stabilize our sample against flux jumping, as well as imply a sweep rate dependence on flux jumps. Bi 2 Sr 2 CaCu 2 O 8+δ crystals are characterized by relatively strong magnetic relaxation caused by flux creep [26,27]. At low temperatures and for a relatively small time window, this magnetic relaxation is logarithmic in time.…”

Section: Discussionmentioning

confidence: 99%

Magnetic flux jumps in texturedBi2Sr2CaCu2

et al. 2003

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Magnetic flux jumps in textured Bi2Sr2CaCu2O 8+δ have been studied by means of magnetization measurements in the temperature range between 1.95 K and Tc, in an external magnetic field up to 9 T. Flux jumps were found in the temperature range 1.95 K -6 K, with the external magnetic field parallel to the c axis of the investigated sample. The effect of sample history on magnetic flux jumping was studied and it was found to be well accounted for by the available theoretical models. The magnetic field sweep rate strongly influences the flux jumping and this effect was interpreted in terms of the influence of both flux creep and the thermal environment of the sample. Strong flux creep was found in the temperature and magnetic field range where flux jumps occur suggesting a relationship between the two. The heat exchange conditions between the sample and the experimental environment also influence the flux jumping behavior. Both these effects stabilize the sample against flux instabilities, and this stabilizing effect increases with decreasing magnetic field sweep rate. Demagnetizing effects are also shown to have a significant influence on flux jumping.

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“…The properties of and phase transitions into the vortex state have been probed with transport [2-6], magnetization [7][8][9][10][11], mechanical oscillator [12], and magnetic decoration techniques [13][14][15][16]. Of these, the transport measurements have shown the clearest evidence for a vortex-glass state.…”

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confidence: 99%

SQUID milliattovoltometry ofYBa2Cu3
Wellstood
¹
,
Ferrari
²
,
Kingston
³

et al. 1993
Phys. Rev. Lett.

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The observation of magnetic flux noise in superconducting thin-film flux transformers of YBa2Cu3-O7-X enables us to measure a very small, frequency-dependent resistance R v (f) in the films, caused by vortex motion. In static magnetic fields below 10~6 T and at voltages down to 10 ~2 0 VHz~1 /2 , R v is proportional to the frequency / at which the measurement is made, is approximately independent of temperature, and decreases with increasing static current in the transformer. This behavior cannot be explained by certain currently accepted models of dissipation arising from vortex motion, but is consistent with a model in which independent vortices hop between two potential wells in a confined region.

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Non-logarithmic magnetic relaxation in Bi2.2Sr1.7CaCu2O8 single crystals; evidence for collective flux pinning

Cited by 45 publications

References 30 publications

Vortices in high-temperature superconductors

Vortices in high-temperature superconductors

Magnetic flux jumps in texturedBi2Sr2CaCu2

SQUID milliattovoltometry ofYBa2Cu3
Wellstood
¹
,
Ferrari
²
,
Kingston
³

et al. 1993
Phys. Rev. Lett.

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Non-logarithmic magnetic relaxation in Bi2.2Sr1.7CaCu2O8 single crystals; evidence for collective flux pinning

Cited by 45 publications

References 30 publications

Vortices in high-temperature superconductors

Vortices in high-temperature superconductors

Magnetic flux jumps in texturedBi2Sr2CaCu2

SQUID milliattovoltometry ofYBa2Cu3Wellstood1, Ferrari2, Kingston3 et al. 1993Phys. Rev. Lett.

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Product

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SQUID milliattovoltometry ofYBa2Cu3
Wellstood
¹
,
Ferrari
²
,
Kingston
³

et al. 1993
Phys. Rev. Lett.