Submillimeter surface impedance and relaxation: A case study of quasi-two-dimensional YBa[sub 2]Cu[sub 3]O[sub x]

Journal Article · Wed Apr 01 04:00:00 EST 1992 · Journal of Superconductivity; (United States)

DOI:https://doi.org/10.1007/BF00618063· OSTI ID:7205488

Halbritter, J ^[1]

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1. Inst. fuer Material und Festkoerperforschung, Karlsruhe (Germany)

Surface impedance measurements in the normal and superconducting state are an excellent method to study the conduction electron dynamics in metals. This holds especially in the relaxation range, i.e., for distances traveled in one r.f. period s = v[sub F]/[omega] (v[sub F] is the Fermi velocity) being smaller or of the order of the penetration depth [lambda] and mean free path l. For materials with v[sub F][le]10[sup 7] cm/sec the relaxation range is easily accessible for f > 0.1 THz. Then, in the normal state, relaxation defines the surface impedance with a penetration depth approaching the London penetration depth [lambda][sub L], and R [approx] [mu][sub 0][lambda][sub L]/2[tau] as surface resistance allowing a measure of [lambda][sub L] and relaxation time [tau](T, [omega]). In the superconducting state the photon interaction scales with [xi][sub F]/[lambda][sub L] = 1/[gamma] ([xi][sub F] is the dimension of Cooper pairs for l[yields][infinity]) and causes at low frequencies an absorption rate growing with [gamma], which is decreasing with [xi][sub F]/l. The rate increase proportional to [gamma] turns to a decrease above 0.1 THz, being accompanied by a decrease of [lambda] with frequency which is stronger for large [gamma] and small [xi][sub F]/l. These characteristic dependences allow a measurement of material parameters, anisotropy, and dynamics of electrons. To evaluate the consequences of the a, b, and c-direction anisotropy, the integral kernels for normal and superconducting surface impedances in its nonintegrated, angle-dependent form are presented, analyzed, and compared with impedance measurements above 0.1 THz of YBa[sub 2]Cu[sub 3]O[sub x]. 28 refs., 5 figs.

• OSTI ID: 7205488
• Journal Information: Journal of Superconductivity; (United States), Journal Name: Journal of Superconductivity; (United States) Vol. 5:2; ISSN JOUSEH; ISSN 0896-1107
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
360207* -- Ceramics
Cermets
& Refractories-- Superconducting Properties-- (1992-)
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
ALKALINE EARTH METAL COMPOUNDS
ANISOTROPY
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
HIGH-TC SUPERCONDUCTORS
IMPEDANCE
MATHEMATICAL MODELS
OXIDES
OXYGEN COMPOUNDS
RELAXATION
SUPERCONDUCTORS
SURFACE PROPERTIES
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS