Superconductivity in layered Nb/Gd films

Journal Article · Tue Feb 01 04:00:00 EST 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.49.4053· OSTI ID:5222476

Strunk, C; Suergers, C; Paschen, U; Loehneysen, H v ^[1]

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1. Physikalisches Institut, Universitaet Karlsruhe, D-76128 Karlsruhe (Germany)

The transition temperature and the critical fields of electron-beam evaporated Nb/Gd/Nb triple layers and Nb/Gd multilayers have been determined by measurements of the electrical resistivity and the dc susceptibility. For constant thickness [ital d][sub Gd] of the Gd layers, we observe a decrease of [ital T][sub [ital c]] and [ital H][sub [ital c]2[perpendicular]] with decreasing thickness [ital d][sub Nb] of Nb layers down to a critical thickness [ital d][sub [ital c]], below which superconductivity is completely destroyed. The parallel critical fields mostly show the square-root temperature dependence near [ital T][sub [ital c]], typical for two-dimensional superconductors. As predicted theoretically, competing pair-breaking mechanisms lead to a nonmonotonic dependence of [ital H][sub [ital c][parallel]] on [ital d][sub Nb]. We have also studied the dependence [ital T][sub [ital c]]([ital d][sub Gd]) with constant [ital d][sub Nb] and find a decrease of the [ital T][sub [ital c]]([ital d][sub Gd]) curve with increasing [ital d][sub Gd] and a steplike structure at [ital d][sub Gd][approx]20 A. To clarify the nature of this step, the ferromagnetic transition of the Gd films is determined with the transverse magneto-optical Kerr effect. Long-range magnetic order is found only above [ital d][sub Gd][approx]20 A, which is attributed to the formation of a discontinuous film below this thickness. These results indicate a change in the underlying pair-breaking mechanism.

• OSTI ID: 5222476
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 49:6; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

665411* -- Basic Superconductivity Studies-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CRITICAL FIELD
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
GADOLINIUM
MAGNETIC FIELDS
METALS
NIOBIUM
PHYSICAL PROPERTIES
RARE EARTHS
SUPERCONDUCTIVITY
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS
TRANSITION TEMPERATURE