In-Plane and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mrow><mml:mover><mml:mrow><mml:mi>c</mml:mi></mml:mrow><mml:mrow><mml:mi>^</mml:mi></mml:mrow></mml:mover></mml:mrow></mml:mrow></mml:math>-Axis Microwave Penetration Depth of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Bi</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub

Jacobs, T.; Sridhar, S.; Li, Qiang; Gu, Genda; Koshizuka, N.

doi:10.1103/physrevlett.75.4516

Cited by 212 publications

(176 citation statements)

References 23 publications

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“…This is interpreted as strong evidence that we have reached the lower critical field H c1 in our measurements. The obtained low-temperature dependence of H c1 is in good agreement with recent microwave absorption measurements of the penetration depth l [13,14]. On the other hand, for specimens with rectangular cross sections, no significant vortex creep over the relevant barriers for vortex entry could be observed, in consistency with theoretical results for geometrical barriers [10].…”

supporting

confidence: 81%

“…At very low sweep rates we found saturated values of the penetration field H p which we interpret as the true lower critical field H c1 . The lowtemperature dependence of H c1 is consistent with recent magnetic penetration depth measurements [13,14] suggesting a superconducting state with nodes in the gap function. Based on the results obtained for Bi2212, we argue that the frequently reported low-temperature upturns of H p in strongly layered superconductors with H perpendicular to the planes [1][2][3][4][5][6] can be explained in terms of measurements where the system is out of equilibrium with respect to barriers for vortex penetration.…”

supporting

confidence: 78%

“…For 11 , T & 30 K, we find a linear behavior l ab ͑T ͒ 2 l ab ͑0͒~T with slope dl͞dT Ӎ 10 Å͞K, where a linear extrapolation to the data gives a T 0 penetration depth l ab ͑0͒ Ӎ 2700 Å. Our measurements thus confirm the linear low-temperature dependence of l ab as well as the slope dl͞dT , which have been recently determined with microwave absorption techniques on clean Bi2212 crystals [13,14]. A linear low-temperature dependence of l ab , as first observed by Hardy et al [19] in YBCO crystals, is consistent with a superconducting state with line nodes on the Fermi surface [20] Figure 4 further shows H p data at high sweep rates ‫.…”

supporting

confidence: 76%

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Lower Critical FieldHc1and Barriers for Vortex Entry inBi2
Nideröst
¹
,
Frassanito
²
,
Saalfrank
³

et al. 1998
Phys. Rev. Lett.
54
8
38
0
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supporting

confidence: 81%

supporting

confidence: 78%

supporting

confidence: 76%

See 1 more Smart Citation

Lower Critical FieldHc1and Barriers for Vortex Entry inBi2
Nideröst
¹
,
Frassanito
²
,
Saalfrank
³

et al. 1998
Phys. Rev. Lett.
54
8
38
0
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“…In HgBa 2 CuO 6+δ it was found that although λ ∼ T , λ ⊥ ∼ T 5 [35], whereas in clean samples of Bi 2 Sr 2 CaCu 2 O 8+δ both λ and λ ⊥ vary linearly with T [36]. The fact that our data show a close to linear T dependence however, supports our conclusion that these materials have low lying excitations.…”

contrasting

confidence: 56%

Low-Temperature Penetration Depth ofκ−(ET)2Cu[N(CN)2
Carrington
¹
,
Bonalde
²
,
Prozorov
³

et al. 1999
Phys. Rev. Lett.
145
19
122
0
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We present high precision measurements of the penetration depth of single crystals of κ−(ET)2Cu[N(CN)2]Br and κ−(ET)2Cu(NCS)2 at temperatures down to 0.4 K. We find that, at low temperatures, the in-plane penetration depth (λ ) varies as a fractional power law, λ ∼ T 3 2 . Whilst this may be taken as evidence for novel pair excitation processes, we show that the data are also consistent with a quasilinear variation of the superfluid density, as is expected for a d-wave superconductor with impurities or a small residual gap. Our data for the interplane penetration depth show similar features and give a direct measurement of the absolute value, λ ⊥ (0) = 100 ± 20 µm.PACS numbers: 74.70. Kn, 74.25.Nf Compounds of the family κ−(ET) 2 X have the highest transition temperatures of all organic superconductors known to date [1]. They have recently attracted considerable attention because of their similarity to the high T c cuprates and the possibility that they may also have a non-conventional paring state [2]. The two materials studied here, κ−(ET) 2 Cu[N(CN) 2 ]Br (T c ∼ 11.6 K) and κ−(ET) 2 Cu(NCS) 2 (T c ∼ 9.6 K), are highly anisotropic, layered, extreme type II superconductors. As in the cuprates, the superconducting phase in these materials is in close proximity to an antiferromagnetic phase. Both antiferromagnetic spin fluctuations and a pseudogap have been detected in NMR measurements in the normal state [3]. Neither the underlying pairing mechanism nor the symmetry of the order parameter has been conclusively established. Although NMR [4,5], specific heat [6] and thermal conductivity [7] measurements all suggest a non-conventional pairing state, results of penetration depth measurements have been inconsistent, with evidence for both conventional [8,9] and non-conventional [10][11][12] behavior. However, none of these penetration depth measurements have been performed over a temperature range (T /T c ) and a precision, comparable to those in the cuprates [13]. In this Letter, we present measurements of both the in-plane λ , and the interplane, λ ⊥ , penetration depths in κ−(ET) 2 Cu[N(CN) 2 ]Br and κ−(ET) 2 Cu(NCS) 2 at temperatures down to 0.4 K.Our measurements were performed on single crystals of κ−(ET) 2 Cu[N(CN) 2 ]Br and κ−(ET) 2 Cu(NCS) 2 which were grown at Argonne National Laboratory. Details of the growth procedures have been given elsewhere [14]. Penetration depth measurements were performed using a 13 MHz tunnel diode oscillator [15] mounted on a 3 He refrigerator. The low noise level [ ∆F F0 ≃ 10 −9 ], and low drift of the oscillator allows us to obtain high resolution data with a very small temperature spacing interval. The samples were attached, with a small amount of vacuum grease, to a sapphire rod which fitted inside the copper sense coil. The sense coil was calibrated using spheres of Aluminum. The sample temperature was measured with a calibrated Cernox thermometer attached to the other end of the sapphire rod. The samples were cooled slowly (0.1-1.0 K/min) to avoid introducing disorder [1...

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“…The numerical calculation for the present case is shown in Fig. 5, for T=70 K, using the experimental values for λ ab (T ) = 245nm [12,20,21], and λ c (T ) = 24.2µm [15] as the (only, experimentally fixed) parameters. We see, that, although the field dependence predicted by the thermal fluctuation model is close to the observations at 70K, still the experimental field dependence is weaker than in the calculation.…”

Section: 72-h7425gzmentioning

confidence: 99%

Effects of Vortex Pinning and Thermal Fluctuations on the Josephson Plasma Resonance inTl2Ba2CaCu2
Dulić
¹
,
Hak
²
,
Marel
³

et al. 2001
Phys. Rev. Lett.
23
0
20
0
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Infrared spectroscopy has been used to investigate the temperature dependence and c-axis magnetic field dependence of the Josephson plasma resonance in optimally doped Tl2Ba2CaCu2O8 thin films, and underdoped YBa2Cu3O6.5 ortho -II single crystals. The resonances are directly related to the c-axis penetration depths, yielding low temperature, zero fields values of about 20 µm, and 7 µm respectively. While the temperature dependencies of the resonances in the two compounds are very similar, the magnetic field dependence in YBCO is much weaker. We attribute this weak magnetic field dependence to the lower anisotropy of YBCO, and discuss the observed behaviours in terms of thermal fluctuations and pinning of pancake vortices, valid for highly anisotropic layered superconductors. 74.25.Gz The Josephson plasma resonance (JPR) phenomenon [1][2][3] provides direct information about the Josephson coupling between the CuO 2 planes in the highly anisotropic high T c superconductors [4]. Studies of the temperature and magnetic field dependence of the JPR provide useful insights into the pinning and thermal fluctuations of vortices in the cuprate family [5][6][7][8][9][10]. It is natural, to anticipate unusual magnetic field behavior in these highly anistropic materials. Indeed, just as in any conventional type-II superconductor, if a DC magnetic field is applied perpendicular to the 2D planes it penetrates the sample in the form of vortices which, when the anisotropy is large, are not vortex lines but pancake vortices. For low magnetic fields and low temperatures, these pancake vortices may form a nearly perfect vortex lattice. Under these conditions there should be no magnetic field dependence of the JPR since ω 2 p (B, T ) = ω 2 p (0) cos(φ n,n+1 )(r) , where ω 2 p (0) is the plasma frequency in zero field, and φ n,n+1 (r) is the gauge-invariant phase difference between the neighboring layers n and n + 1 [8]. In zero field, φ n (r) is independent of r and independent of n for zero c-axis current. In non-zero field, φ n (r) becomes position dependent but φ n,n+1 (r) is everywhere zero, provided the vortex cores are lined up, as in a perfect lattice. However, due to the effects of pinning (at low temperatures), and thermal fluctuations (at higher temperatures) pancake vortices do not in general line up from layer to layer. Both regimes have been extensively studied theoretically by Bulaevskii and one of us (AEK) [9][10][11], but there is very little data on the JPR in the low magnetic field regime [7]. In this paper we present our studies of the temperature and field dependence of the JPR in two members of the high T c family with differing anisotropies.Two types of reflectivity spectra were measured, each optimized to the type of sample: First normal incidence reflectivity spectra were recorded of a mosaic made of six ac-oriented single crystals of YBa 2 Cu 3 O 6.5 with ortho-II oxygen ordering, and a superconducting transition temperature of 58K. The mosaic was held together with epoxy and had an area of 6mm 2 . Second...

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In-Plane andc^-Axis Microwave Penetration Depth ofBi2

Cited by 212 publications

References 23 publications

Lower Critical FieldHc1and Barriers for Vortex Entry inBi2
Nideröst
¹
,
Frassanito
²
,
Saalfrank
³

et al. 1998
Phys. Rev. Lett.
54
8
38
0
View full text Add to dashboard Cite

Lower Critical FieldHc1and Barriers for Vortex Entry inBi2
Nideröst
¹
,
Frassanito
²
,
Saalfrank
³

et al. 1998
Phys. Rev. Lett.
54
8
38
0
View full text Add to dashboard Cite

Low-Temperature Penetration Depth ofκ−(ET)2Cu[N(CN)2
Carrington
¹
,
Bonalde
²
,
Prozorov
³

et al. 1999
Phys. Rev. Lett.
145
19
122
0
View full text Add to dashboard Cite

Effects of Vortex Pinning and Thermal Fluctuations on the Josephson Plasma Resonance inTl2Ba2CaCu2
Dulić
¹
,
Hak
²
,
Marel
³

et al. 2001
Phys. Rev. Lett.
23
0
20
0
View full text Add to dashboard Cite

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In-Plane andc^-Axis Microwave Penetration Depth ofBi2

Cited by 212 publications

References 23 publications

Lower Critical FieldHc1and Barriers for Vortex Entry inBi2Nideröst1, Frassanito2, Saalfrank3 et al. 1998Phys. Rev. Lett.548380View full textAdd to dashboardCite

Lower Critical FieldHc1and Barriers for Vortex Entry inBi2Nideröst1, Frassanito2, Saalfrank3 et al. 1998Phys. Rev. Lett.548380View full textAdd to dashboardCite

Low-Temperature Penetration Depth ofκ−(ET)2Cu[N(CN)2Carrington1, Bonalde2, Prozorov3 et al. 1999Phys. Rev. Lett.145191220View full textAdd to dashboardCite

Effects of Vortex Pinning and Thermal Fluctuations on the Josephson Plasma Resonance inTl2Ba2CaCu2Dulić1, Hak2, Marel3 et al. 2001Phys. Rev. Lett.230200View full textAdd to dashboardCite

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About

Lower Critical FieldHc1and Barriers for Vortex Entry inBi2
Nideröst
¹
,
Frassanito
²
,
Saalfrank
³

et al. 1998
Phys. Rev. Lett.
54
8
38
0
View full text Add to dashboard Cite

Lower Critical FieldHc1and Barriers for Vortex Entry inBi2
Nideröst
¹
,
Frassanito
²
,
Saalfrank
³

et al. 1998
Phys. Rev. Lett.
54
8
38
0
View full text Add to dashboard Cite

Low-Temperature Penetration Depth ofκ−(ET)2Cu[N(CN)2
Carrington
¹
,
Bonalde
²
,
Prozorov
³

et al. 1999
Phys. Rev. Lett.
145
19
122
0
View full text Add to dashboard Cite

Effects of Vortex Pinning and Thermal Fluctuations on the Josephson Plasma Resonance inTl2Ba2CaCu2
Dulić
¹
,
Hak
²
,
Marel
³

et al. 2001
Phys. Rev. Lett.
23
0
20
0
View full text Add to dashboard Cite