Showing papers by "Barry L. Zink published in 2004"
TL;DR: In this paper, specific heat and thermal conductivity of low-stress amorphous silicon-nitride thin-films were determined from measurements using a membrane-based microcalorimeter.
131 citations
11 Mar 2004-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the authors describe the design, fabrication and performance of a fully lithographically patterned magnetic microcalorimeter X-ray detector, which is fabricated on the same chip as a low-noise SQUID that measures the change in the magnetic sensor film's magnetization as the film is heated by absorbed X-rays.
Abstract: We describe the design, fabrication and performance of a fully lithographically patterned magnetic microcalorimeter X-ray detector. The detector is fabricated on the same chip as a low-noise SQUID that measures the change in the magnetic sensor film's magnetization as the film is heated by absorbed X-rays. Our proof-of-principle detectors use a 100 μm ×100 μm – 2 μm paramagnetic Au:Er film coupled to a low-noise on-chip SQUID via a meandering superconducting pickup loop that also provides the magnetic field bias to the film. Absorption of 6 keV X-rays in the film causes heating on the order of 1 mK with a decay time of 1 ms or less, the fastest reported using a magnetic calorimeter. However, the resolution is currently poor due to poor Au:Er film properties and non-optimized coupling to the SQUID. We describe the design and fabrication of this device and present measurements of the heat capacity, decay time constant and effective thermal conductance of the microcalorimeter as a function of temperature. Because the SQUID and calorimeter are lithographically patterned on the same substrate, this technology can be readily applied to the fabrication of arrays of multiplexed magnetic microcalorimeter detectors.
12 citations
TL;DR: In this paper, the specific heat and magnetization temperature in a single crystal sample of superconducting La$2}$CuO$4.11$ and in a sample of the same material after removing the excess oxygen, in magnetic fields up to 15 T.
Abstract: We have measured the specific heat and magnetization {\it versus} temperature in a single crystal sample of superconducting La$_{2}$CuO$_{4.11}$ and in a sample of the same material after removing the excess oxygen, in magnetic fields up to 15 T. Using the deoxygenated sample to subtract the phonon contribution, we find a broad peak in the specific heat, centered at 50 K. This excess specific heat is attributed to fluctuations of the Cu spins possibly enhanced by an interplay with the charge degrees of freedom, and appears to be independent of magnetic field, up to 15 T. Near the superconducting transition $T_{c}$($H$=0)= 43 K, we find a sharp feature that is strongly suppressed when the magnetic field is applied parallel to the crystallographic c-axis. A model for 3D vortex fluctuations is used to scale magnetization measured at several magnetic fields. When the magnetic field is applied perpendicular to the c-axis, the only observed effect is a slight shift in the superconducting transition temperature.
7 citations