Current Filamentation in LargeBi2Sr2CaCu2O8

Abstract

We have studied the self-heating of a large stack of Bi 2 Sr 2 CaCu 2 O 8+δ intrinsic Josephson junctions, of a configuration designed for THz generation. We find good qualitative agreement between direct thermoluminescent measurements of the device surface temperature and low-temperature scanning laser microscopy images. In particular, the two techniques both reveal a novel mode of thermal instability through the asymmetric nucleation of a small hot-spot near a corner/edge of the sample. This behavior conforms with a theoretical stability analysis, and the radius of the hot-spot is in excellent agreement with theoretical predictions, as is its growth with increasing bias current and bath temperature. Narrow hot-spots may offer a new possible means of enhancing the terahertz emission power from this type of device.

High-resolution Thermal Micro-imaging Using Europium Chelate Luminescent Coatings

“…their crystalline c-axis) described above. Not only do they experimentally show complex inhomogeneous self-heating behavior 5,6,7,8,9,10,11 it has been theoretically predicted that this may be beneficial for THz power emission 12,13 .…”

A high-resolution combined scanning laser and widefield polarizing microscope for imaging at temperatures from 4 K to 300 K

“…It was shown by Dieckmann et al 69 that this technique, lowtemperature scanning laser microscopy (LTSLM), delivers results that are equivalent to LTSEM. LTSLM has, among others, been applied to research on superconductors 32,34,70,71 , the quantum Hall effect 72 , spintronics 73,74 and spin-caloritronics 75 . The LTSPM can be operated in LTSLM mode to gain information on the electric trans- port properties of a sample.…”

“…The confocal laser scanning microscope offers an additional imaging mechanism: a beam-induced voltage across a currentbiased sample can be generated by the local perturbation of the laser beam. This beam-induced voltage can be used to extract local information on the electric transport properties of the sample [30][31][32][33][34] . While several examples of low-temperature widefield [35][36][37] and laser scanning polarizing microscopes [38][39][40] have been published, the instrument presented here stands out with regard to the versatility offered by combining widefield and confocal laser scanning imaging modes, the accessible temperature range, as well as the very high lateral resolution it provides at low temperatures.…”

Engineering and characterization of a packaged high-Tcsuperconducting terahertz source module

“…For comparison, the tunability of a single RTD source is 5% at best [19]. Previous studies have shown that the thermal management of emitting sources is a key requirement for controlling their characteristics [20,21,22,23,24,25,26,27,28,29,30,31,32,33,34]. Previously, radiation above 1 THz was achieved by an improved cooling technique [27].…”