Current distribution and transition width in superconducting transition-edge sensors

Abstract

Present models of the superconducting-to-normal transition in transition-edge sensors (TESs) do not describe the current distribution within a biased TES. This distribution is complicated by normal-metal features that are integral to TES design. We present a model with one free parameter that describes the evolution of the current distribution with bias. To probe the current distribution experimentally, we fabricated TES devices with different current return geometries. Devices where the current return geometry mirrors current flow within the device have sharper transitions, thus allowing for a direct test of the current-flow model. Measurements from these devices show that current meanders through a TES low in the resistive transition but flows across the normal-metal features by 40% of the normal-state resistance. Comparison of transition sharpness between device designs reveals that self-induced magnetic fields play an important role in determining the width of the superconducting transition. [http://dx.doi.org/10.1063/1.4771984]

5 pages, 4 figures

References in corpus (3)

• The Atacama Cosmology Telescope: A Measurement of the Cosmic Microwave Background Power Spectrum at 148 and 218 GHz from the 2008 Southern Survey
• Longitudinal Proximity Effects in Superconducting Transition-Edge Sensors
• Current distribution and transition width in superconducting transition-edge sensors

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• A Two-Dimensional Resistor Network Model for Transition-Edge Sensors with Normal Metal Features
• Proximity effect model for x-ray Transition Edge Sensors