Local Measurement of Superfluid Density in Ba(Fe1-xCox)2As2 Single Crystals by Magnetic Scanning Probes
报告人:
Lan Luan
Department of applied physics, Stanford University
报告时间:
2009-09-17 10:30
报告地点:
物理系 2406会议室
主办单位:
物理系
简介:
报告摘要：We measure the local penetration depth and its temperature induced change in Ba(Fe1-xCox)2As2 (x ≈ 0.051,Tc = 18.5K ) single crystals by magnetic force microscopy (MFM) and scanning SQUID suspetometry (SSS). We observe that the penetration depth varies about ten times slower with temperature than previously published, with a dependence that can be well described from 0.4 K to Tc by a clean two-band fully gapped model. We demonstrate that MFM can determine the important and hard-to-measure absolute value of the superfluid density, while obtaining its temperature dependence and spatial homogeneity in the same measurement. We observe in SSS scans stripes of increased diamagnetic susceptibility that suggest enhanced superfluid density on twin boundaries. These stripes only appear in samples with structural domains, providing direct evidence that areas of enhanced local strain and frustrated magnetism also have enhanced superfluid density.
