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A. Purnell

Publications and source records attributed to A. Purnell.

2 recordsLinked to original sources
arXiv2001

Microwave Power, DC Magnetic Field, Frequency and Temperature Dependence of the Surface Resistance of MgB2

The microwave power, dc magnetic field, frequency and temperature dependence of the surface resistance of MgB2 films and powder samples were studied. Sample quality is relatively easy to identify by a number of characteristics, the most clear being the breakdown in the omega squared law for poor quality samples. Analysis of the experimental data suggests the most attractive procedure for high quality film growth for technical applications.

cond-mat.supr-con↗
arXiv2001

Temperature dependence of the microwave surface impedance measured on different kinds of MgB$_2$ samples

In this paper we present the results of measurements of the microwave surface impedance of a powder sample and two films of MgB$_2$. One film has $T_c=30$ K and is not textured, the other is partially c-axis orientated with $T_c=38$ K. These samples show different types of temperature dependence of the field penetration depth: linear for the powder sample, exponential with $Δ/kT_c<1.76$ (film with $T_c=30$ K) and strong coupling behaviour with $Δ/kT_c\sim 2.25$ (film with $T_c=38$ K). The results are well described in terms of an anisotropic gap model or presence of a slightly deficient MgB$_2$ phase. The data set for all samples - taken as a whole cannot be fitted into a two gap scenario.

cond-mat.supr-con↗