arXiv subjects

L. V. Mercaldo

Publications and source records attributed to L. V. Mercaldo.

3 recordsLinked to original sources

arXiv2001

Scaling of H_{c2 \perp}(T) in Nb/CuMn Multilayers

Measurements of the perpendicular upper critical magnetic field H_{c2 \perp}(T) are reported for several Nb/CuMn multilayers. It is found that, despite the magnetic nature of the samples, the data for samples with low Mn percentage in the CuMn layers are simply described by the Werthamer-Helfand-Honenberg theory for conventional type-II superconductors, neglecting both Pauli spin paramagnetism and spin orbit impurity scattering. For high Mn concentration a different theoretical aprroach is needed.

cond-mat.supr-con↗

arXiv2000

Irreversibility Line in Nb/CuMn Multilayers with a Regular Array of Antidots

The transport properties of Nb/CuMn multilayers with a regular array of electron beam lithography obtained antidots have been measured at different temperatures in the presence of external perpendicular magnetic fields. Hysteretical I-V characteristics have been observed which disappear when approaching the upper critical magnetic field curve H_{c2}(T). Comparing these data with other results (Arrhenius plots of resistive transition curves, logV-logI characteristics) we have been able to relate the onset of the hysteresis to the presence of an irreversibility line. We discuss several possible mechanisms to clarify the nature of this line. Among them the most plausible seems to be the vortex melting mainly induced by quantum fluctuations.

cond-mat.supr-con↗

arXiv1998

Microwave surface impedance of proximity-coupled superconducting (Nb) / spin-glass (CuMn) bilayers

The surface impedance of Nb/CuMn (superconducting/spin-glass) bilayers has been measured at 10 GHz with the parallel plate resonator technique to obtain information about the exotic behavior of the order parameter in superconducting/magnetic proximity systems. The data strongly differs from the superconducting/normal-metal case, showing the magnetic nature of the CuMn layer, which acts as a weak ferromagnet. The results are described in the framework of two models for the electrodynamics of superconducting/ferromagnetic (S/M) bilayers characterized by a proximity-coupling length scale which is independent of temperature.

cond-mat.supr-con↗