Eley Serena, Willa Roland, Chan Mun K, Bauer Eric D, Civale Leonardo
Department of Physics, Colorado School of Mines, Golden, CO, 80401, USA.
Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
Sci Rep. 2020 Jun 24;10(1):10239. doi: 10.1038/s41598-020-65224-5.
We present an extensive study of vortex dynamics in a high-quality single crystal of HgBaCuO, a highly anisotropic superconductor that is a model system for studying the effects of anisotropy. From magnetization M measurements over a wide range of temperatures T and fields H, we construct a detailed vortex phase diagram. We find that the temperature-dependent vortex penetration field H(T), second magnetization peak H(T), and irreversibility field H(T) all decay exponentially at low temperatures and exhibit an abrupt change in behavior at high temperatures T/T >~ 0.5. By measuring the rates of thermally activated vortex motion (creep) S(T, H) = |dlnM(T, H)/dlnt|, we reveal glassy behavior involving collective creep of bundles of 2D pancake vortices as well as temperature- and time-tuned crossovers from elastic (collective) dynamics to plastic flow. Based on the creep results, we show that the second magnetization peak coincides with the elastic-to-plastic crossover at low T, yet the mechanism changes at higher temperatures.
我们对HgBaCuO高质量单晶中的涡旋动力学进行了广泛研究，HgBaCuO是一种高度各向异性的超导体，是研究各向异性效应的模型系统。通过在很宽的温度T和磁场H范围内进行磁化强度M测量，我们构建了详细的涡旋相图。我们发现，与温度相关的涡旋穿透场H(T)、第二磁化峰H(T)和不可逆场H(T)在低温下均呈指数衰减，而在高温T/T >~ 0.5时行为发生突变。通过测量热激活涡旋运动（蠕动）速率S(T, H) = |dlnM(T, H)/dlnt|，我们揭示了涉及二维煎饼状涡旋束集体蠕动的玻璃态行为，以及从弹性（集体）动力学到塑性流动的温度和时间调谐交叉。基于蠕动结果，我们表明第二磁化峰在低温下与弹性到塑性的交叉点重合，但在较高温度下机制会发生变化。
