Weakly Pinned Bose Glass vs Mott Insulator Phase in Superconductors

Wengel, Carsten; Täuber, Uwe C.

doi:10.1103/physrevlett.78.4845

Cited by 39 publications

(30 citation statements)

References 18 publications

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“…This Mott insulator can be viewed as a Meissner phase for vortices at the matching field instead of zero field. 12,19 In Ref. 19 by doing a zero-temperature calculation ͑thereby ignoring vortex wandering͒ it was argued that such a Mott-insulator phase is seen only for short-range interactions and is taken over by a weakly pinned Bose-glass phase with finite or long-range interactions.…”

Section: A Pinning Disordermentioning

confidence: 99%

“…12,19 In Ref. 19 by doing a zero-temperature calculation ͑thereby ignoring vortex wandering͒ it was argued that such a Mott-insulator phase is seen only for short-range interactions and is taken over by a weakly pinned Bose-glass phase with finite or long-range interactions. We note that, since we consider strictly local interactions in the hard-core limit, we access this Mott insulator even at finite temperatures.…”

Section: A Pinning Disordermentioning

confidence: 99%

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Competition between columnar pins and vortex screening: A doubly reentrant phase diagram

2002

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We study the phase diagram of flux lines in superconductors with columnar pins. Based on numerical exact diagonalization simulations on small clusters, we get two phases of vortices: A low-temperature pinned glass with diverging tilt modulus and a high-temperature delocalized entangled vortex liquid. For random potential disorder we find a new phase transition temperature T BG from a pinned Bose glass to an entangled liquid that reduces with increasing vortex density. This occurs primarily because vortices screen the disorder potential and generate an effective weaker random potential with increasing vortex density. For a fixed fraction of randomly placed attractive columnar pins, we find a Mott-insulating phase when the vortex density exactly matches the density of pins at the matching field BϭB . We also find a transition from a strongly pinned Bose glass for BϽB to a weakly pinned Bose glass for BϾB as the vortex density is varied.

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Section: A Pinning Disordermentioning

confidence: 99%

Section: A Pinning Disordermentioning

confidence: 99%

Competition between columnar pins and vortex screening: A doubly reentrant phase diagram

2002

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“…In this phase all vortices are locked onto a column and the compressibility (ϰc 11 Ϫ1 ) of the vortex system is zero leading to a fixed induction over a finite field interval. Although the interplay between the random positions of the CD's and intervortex interactions prevents the occurrence of a true Mott insulator, 19 the relative increase in pinning energy with respect to the intervortex interaction for higher ␣ drives the system closer to the Mott insulator phase. We note that the features of the Mott insulator phase should be more pronounced at very low temperatures where the pinning energy of CD's exceeds all other energy scales.…”

Section: ͑3͒mentioning

confidence: 99%

Tuning the pinning energy in layered superconductors

et al. 1999

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Reversible magnetization measurements show that the pinning energy of vortices localized on amorphous tracks created in Bi 2 Sr 2 CaCu 2 O 8 single crystals by heavy-ion irradiation can be adjusted by altering the irradiation angle. The pinning energy is found to be proportional to the cross-sectional area of the defects in the CuO 2 planes. Both this size dependence and the observed quadratic temperature dependence of the pinning energy imply a predominant vortex core pinning interaction of pancake vortices with columnar defects as opposed to an electromagnetic pinning mechanism. An independent determination of the value of the Ginzburg-Landau coherence length is also presented. ͓S0163-1829͑99͒00321-5͔Fundamental studies of flux pinning and critical currents in ͑high temperature͒ superconductors ͑HTSC's͒ require pinning-center configurations with well-defined properties. Amorphous columnar defects ͑CD's͒ produced in HTSC's by heavy ion-irradiation 1-3 ͑HII͒ are among these because their size, physical properties, and spatial distribution can be well characterized by high-resolution electron microscopy ͑HREM͒ and scanning tunneling microscopy. The circular cross section of the ion tracks, of size comparable to that of the vortex core, facilitates an estimate of the elementary pinning energy and pinning force; 4-8 the irradiation dose determines the average concentration, usually expressed in terms of the dose equivalent field B ϭ⌽ 0 n d , where ⌽ 0 is the flux quantum and n d is the areal density of CD's. Furthermore, in layered systems such as Bi 2 Sr 2 CaCu 2 O 8 , the background pinscape at high temperature is virtually smooth so that the pinning properties are especially well defined. This paper will concentrate on an additional property of CD's, unique to layered superconductors, which can easily be realized experimentally. Since the order-parameter magnitude in the intermediate BiO layers is very small, vortices in Bi 2 Sr 2 CaCu 2 O 8 should be viewed as stacks of ''pancake'' vortices in the superconducting CuO 2 double layers. Only those defects that reside in the CuO 2 layers can therefore be expected to be effective pinning centers. As for CD's, only their intersection with these layers will be relevant. This will be explicitly demonstrated below: we will show that the pancake pinning energy is proportional to the damaged area in the CuO 2 planes, when this is varied by irradiation in different directions.The pinning energy per unit length U 0 of a vortex trapped on a CD of radius c 0 consists of a core contribution U 0 c and an electromagnetic part U 0 em . The latter arises because of the modification of the vortex current when the vortex core is replaced by an amorphous track. It is important only when the track radius exceeds that of the vortex core, i.e., c 0 ӷͱ2 ab , and is given by 4-7Here 0 ϭ2 0 H c 2 ab 2 ϭ⌽ 0 2 /4 0 ab 2 , H c is the thermodynamic critical field, ab is the Ginzburg-Landau ͑GL͒ penetration depth, and ab is the GL coherence length. In the case where c 0 Ӷͱ2 ab the core contribu...

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“…30 The importance of intralayer pancake repulsion is often downplayed, even though it has been shown to be important in determining the pancake arrangement, 31 reversible magnetization, 14,31 and transport properties. 31 It is the purpose of this paper to investigate the importance of the contributions of intra-and interlayer pancake vortex interaction energy, entropy, and pinning energy to the Gibbs free energy G, and the impact of each on the phase diagram of heavy-ion irradiated Bi 2 Sr 2 CaCu 2 O 8+δ . To this effect, we have performed reversible magnetization as well as AC screening measurements on heavy-ion irradiated Bi 2 Sr 2 CaCu 2 O 8+δ with widely varying matching fields (section II).…”

Section: Introductionmentioning

confidence: 99%

Entropy, vortex interactions, and the phase diagram of heavy-ion-irradiatedBi2Sr2CaCu
Beek
¹
,
Kończykowski
²
,
Drost
³

et al. 2000
Phys. Rev. B
40
3
29
0
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Dynamic and thermodynamic magnetization experiments on heavy-ion irradiated single crystalline Bi2Sr2CaCu2O 8+δ are correlated in order to clarify the nature of the mixed state phase diagram. It is shown that whereas the entropy contribution to the free energy in the London regime plays a minor role in unirradiated crystals and irradiated crystals at fields close to or above the matching field B φ , it becomes very important at low fields in irradiated crystals with high B φ . The direct determination of the entropy contribution to the free energy from the reversible magnetization allows one to determine not only the correct values of the pinning energy, but also to extract quite detailed information on pancake vortex alignment. The characteristic field Hint ∼ 1 6 B φ at which intervortex repulsion begins to determine the vortex arrangement and the reversible magnetization is shown to coincide with a sharp increase in the irreversibility field Hirr(T ) and with the recoupling transition found in Josephson Plasma Resonance. Above Hint, the repulsive interaction between vortices cause both the vortex mobility to decrease and pancake alignement to increase. At higher fields > ∼ 1 3 B φ ≫ Bc1, free vortices outnumber those that are trapped on a columnar defect. This causes the decrease of c-axis resistivity and a second crossover of the irreversibility field, to a regime where it is determined by plastic creep.74.60. Ec,74.40.Jg,74.60.Ge

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Weakly Pinned Bose Glass vs Mott Insulator Phase in Superconductors

Cited by 39 publications

References 18 publications

Competition between columnar pins and vortex screening: A doubly reentrant phase diagram

Competition between columnar pins and vortex screening: A doubly reentrant phase diagram

Tuning the pinning energy in layered superconductors

Entropy, vortex interactions, and the phase diagram of heavy-ion-irradiatedBi2Sr2CaCu
Beek
¹
,
Kończykowski
²
,
Drost
³

et al. 2000
Phys. Rev. B
40
3
29
0
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Weakly Pinned Bose Glass vs Mott Insulator Phase in Superconductors

Cited by 39 publications

References 18 publications

Competition between columnar pins and vortex screening: A doubly reentrant phase diagram

Competition between columnar pins and vortex screening: A doubly reentrant phase diagram

Tuning the pinning energy in layered superconductors

Entropy, vortex interactions, and the phase diagram of heavy-ion-irradiatedBi2Sr2CaCuBeek1, Kończykowski2, Drost3 et al. 2000Phys. Rev. B403290View full textAdd to dashboardCite

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Entropy, vortex interactions, and the phase diagram of heavy-ion-irradiatedBi2Sr2CaCu
Beek
¹
,
Kończykowski
²
,
Drost
³

et al. 2000
Phys. Rev. B
40
3
29
0
View full text Add to dashboard Cite