Microwave properties of RE–Ni2B2C (RE=Y, Er) superconducting thin films

Andreone, A.; Aruta, C.; Iavarone, M.; Palomba, F.; Russo, Ml; Salluzzo, M.; Vaglio, R.; Cassinese, A.; Hein, Matthias; Kaiser, Thomas; Müller, Günter; Perpeet, M.

doi:10.1016/s0921-4534(99)00305-6

Cited by 7 publications

(5 citation statements)

References 33 publications

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“…We see the following features: 1) onset of superconductivity at T * c = 11.3 K, 2) a slight shoulder at T N = 6.0 K, 3) a broad peak at T W F M = 2.3 K, 4) another sharp peak at T m = 0.45 K, and 5) an eventual downturn below T m . The features at T N and T W F M have not been seen in previous microwave measurements of ∆λ(T ) on either thin-film [19] or single-crystal ErNi 2 B 2 C [20], but the former has been observed in SANS data [21]. We show in a separate publication [22] that the feature at T N is only observed for relatively small non-magnetic scattering rates.…”

supporting

confidence: 45%

“…In conclusion, penetration depth data of single-crystal ErNi 2 B 2 C down to ∼0.1 K provide strong evidence for the existence of a spontaneous vortex phase below T W F M . The high quality of our sample enables us to see features at T N and T W F M that have not been observed in previous studies of the penetration depth [18,19]. Other samples, such as that shown in the inset to Fig.…”

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confidence: 72%

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Observation of the spontaneous vortex phase in the weakly ferromagnetic superconductor ErNi ₂ B ₂ C: A penetration depth study

et al. 2006

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The coexistence of weak ferromagnetism and superconductivity in ErNi2B2C suggests the possibility of a spontaneous vortex phase (SVP) in which vortices appear in the absence of an external field. We report evidence for the long-sought SVP from the in-plane magnetic penetration depth ∆λ(T ) of high-quality single crystals of ErNi2B2C. In addition to expected features at the Néel temperature TN = 6.0 K and weak ferromagnetic onset at TW F M = 2.3 K, ∆λ(T ) rises to a maximum at Tm = 0.45 K before dropping sharply down to ∼0.1 K. We assign the 0.45 K-maximum to the proliferation and freezing of spontaneous vortices. A model proposed by Koshelev and Vinokur explains the increasing ∆λ(T ) as a consequence of increasing vortex density, and its subsequent decrease below Tm as defect pinning suppresses vortex hopping.

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supporting

confidence: 45%

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confidence: 72%

Observation of the spontaneous vortex phase in the weakly ferromagnetic superconductor ErNi ₂ B ₂ C: A penetration depth study

et al. 2006

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“…Similarly, studies of microwave dissipation and relaxation in magnetic or dielectric materials have received great attention recently, e.g., to resolve the coupling of spins and charges in magnetic superconductors like the borocarbides or rutheno-cuprates [6,7,8], or materials displaying colossal magneto-resistance [9], or to search for low-loss ferrite or ferroelectric materials for frequency-agile devices [10,11,12]. …”

Section: Theoretical Backgroundmentioning

confidence: 99%

Recent developments in the characterization of superconducting films by microwaves

Hein

Getta

Kreiskott

et al. 2002

Physica C: Superconductivity

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We describe and analyze selected surface impedance data recently obtained by different groups on cuprate, ruthenate and diboride superconducting films on metallic and dielectric substrates for fundamental studies and microwave applications. The discussion includes a first review of microwave data on MgB 2 , the weak-link behaviour of RABiTS-type YBa 2 Cu 3 O 7-δ tapes, and the observation of a strong anomalous powerdependence of the microwave losses in MgO at low temperatures. We demonstrate how microwave measurements can be used to investigate electronic, magnetic, and dielectric dissipation and relaxation in the films and substrates. The impact of such studies reaches from the extraction of microscopic information to the engineering of materials and further on to applications in power systems and communication technology.Keywords: Surface impedance, superconducting films, microwave dissipation, relaxation.Address: Dr. Matthias Hein, Dept. of Physics, Univ. of Wuppertal, D-42097 Wuppertal, Germany. Tel. +49(202) 439-2747, Fax +49(202) Email: mhein@venus.physik.uni-wuppertal.de M. Hein et al., EUCAS 2001, invited paper B3-01, page 2 of 19 Microwave measurements in condensed matter physics Theoretical backgroundThis paper illustrates the relevance of microwave measurements for the investigation of electronic and magnetic transport and ordering in condensed matter. While most work has been done on solids, the described techniques could also be adapted to soft matter or liquids.The presentation is based on a selection of examples and does not attempt to provide a complete description of activities in this field.The complex-valued surface impedance Z s =R s +iX s at a microwave frequency ω=2πf is related to the permeability and conductivity of a material, µ and σ, in the local limit by ) (where R s and X s are the surface resistance and reactance [1]. The material parameters µ and σ are complex-valued and frequency dependent, e.g., via electronic, magnetic, or dielectric relaxation. The generalized conductivity σ characterizes electrical conduction through transport and displacement currents.The electrodynamic response of metallic materials provides information on the electronic properties within a surface layer of the order of the London penetration depth ~200 nm, and on a variable time scale ∼1/ω. Such information is complementary to thermodynamic bulk properties and low-frequency transport data. The high frequencies also help to derive Fermi surface properties, which would require strong magnetic fields at very low temperatures otherwise [2]. We will focus in the following on superconductors, for which Z s bears information on the density of states and quasiparticle excitations above and below the transition temperature T c [3]. It is also related to the phase purity, grain connectivity and interface effects of technical materials, which cannot readily be studied at similar resolution by At present at least 50 renowned academic and industrial groups study superconductors at microwave frequencies, to ...

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“…In this geometry, the propagating wave is a TEM-mode, with E and H perpendicular to the film surface. Details of each measurement procedure and a comparison between the two techniques have been reported elsewhere [16][17][18].…”

Section: Microwave Responsementioning

confidence: 99%

Synthesis and microwave properties of TI2Ba2CaCu2O8 superconducting films grown by MOCVD

Pica¹,

Andreone²,

Palomba³

et al. 2000

Eur. Phys. J. B

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We report on the synthesis, structural and electrical characterization of high quality Tl2Ba2Ca1Cu2O8 (Tl-2212) superconducting films. The samples have been grown ex-situ on 10 × 10 mm 2 LaAlO3 (100) substrates by a combined approach of metal-organic chemical vapor deposition (MOCVD) and thallium vapor diffusion. The morphological and compositional nature of the c-axis oriented films has been investigated by SEM and X-ray analyses. Typical values of Tc = 104 K and Jc = 0.5 MA/cm 2 at 77 K have been measured. Microwave measurements have been performed at f = 87 GHz inserting the film in a copper cavity and at f = 1.5 GHz on patterned samples using a microstrip resonator technique. A penetration depth λ(0) = 400 nm is evaluated by fitting the microwave data with phenomenological equations. The minimum value of the surface resistance Rs measured at 4.2 K is 60 µΩ and 6 mΩ at 1.5 GHz and 87 GHz respectively. The microwave data are described in the context of a modified two fluid model. An evaluation of the temperature dependence of the scattering rate has been performed through the simultaneous measurement of the surface resistance and the penetration depth.

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Microwave properties of RE–Ni2B2C (RE=Y, Er) superconducting thin films

Cited by 7 publications

References 33 publications

Observation of the spontaneous vortex phase in the weakly ferromagnetic superconductor ErNi ₂ B ₂ C: A penetration depth study

Observation of the spontaneous vortex phase in the weakly ferromagnetic superconductor ErNi ₂ B ₂ C: A penetration depth study

Recent developments in the characterization of superconducting films by microwaves

Synthesis and microwave properties of TI2Ba2CaCu2O8 superconducting films grown by MOCVD

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Microwave properties of RE–Ni2B2C (RE=Y, Er) superconducting thin films

Cited by 7 publications

References 33 publications

Observation of the spontaneous vortex phase in the weakly ferromagnetic superconductor ErNi 2 B 2 C: A penetration depth study

Observation of the spontaneous vortex phase in the weakly ferromagnetic superconductor ErNi 2 B 2 C: A penetration depth study

Recent developments in the characterization of superconducting films by microwaves

Synthesis and microwave properties of TI2Ba2CaCu2O8 superconducting films grown by MOCVD

Contact Info

Product

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Observation of the spontaneous vortex phase in the weakly ferromagnetic superconductor ErNi ₂ B ₂ C: A penetration depth study

Observation of the spontaneous vortex phase in the weakly ferromagnetic superconductor ErNi ₂ B ₂ C: A penetration depth study