Submitted on 23 Aug 2018 (v1), last revised (Aug) (this version, v3))
Abstract:Recent predictions and experimental observations of high Tc superconductivity in hydrogen-rich materials at very high pressures are driving the search for superconductivity in the vicinity of room temperature. We have developed a novel preparation technique that is optimally suited for megabar pressure syntheses of superhydrides using pulsed laser heating while maintaining the integrity of sample-probe contacts for electrical transport measurements to 200 GPa. We detail the synthesis and characterization, including four-probe electrical transport measurements, of lanthanum superhydride samples that display a significant drop in resistivity on cooling beginning around 260 K and pressures of 190 GPa . Additional measurements on two additional samples synthesized the same way show resistance drops beginning as high as 280 K at these pressures. The loss of resistance at these high temperatures is not observed in control experiments on pure La as well as in partially transformed samples at these pressures, and x-ray diffraction as a function of temperature on the superhydride reveal no structural changes on cooling. We infer that the resistance drop is a signature of the predicted room-temperature superconductivity in LaH 10, in good agreement with density functional structure search and BCS theory calculations.
From: Maddury Somayazulu [view email]
[v1] Thu, (Aug) 10: 54: 43 UTC (747
[v2] Mon, 27 Aug 2018 00: 01: (UTC) ************************************** (KB)
[v3]Wed, 29 Aug 2018 12: 17: (UTC) (KB)
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