Direct imaging of the structural domains in iron pnictides AFe2As2 (A = Ca, Sr, Ba)
Direct imaging of the structural domains in iron pnictides AFe2As2 (A = Ca, Sr, Ba)
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DOI：
10.1103/physrevb.79.180508
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发表时间：
2009-04
期刊：
影响因子：
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通讯作者：
M. Tanatar;A. Kreyssig;S. Nandi;N. Ni;S. Bud’ko;P. Canfield;A. Goldman;R. Prozorov
中科院分区：
文献类型：
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作者：
M. Tanatar;A. Kreyssig;S. Nandi;N. Ni;S. Bud’ko;P. Canfield;A. Goldman;R. Prozorov
新发现的砷化铁超导体的母体化合物：碱土为：A=Ca，Sr，Ba的超导体的母体化合物在温度为T_(SM)时，同时发生结构相变和磁性相变。用偏光显微镜和空间分辨高能同步X射线衍射仪相结合的方法，我们发现在所有的母体化合物中，正交形变导致了4500型结构域的形成。磁区沿c方向穿透样品厚度，不受晶体缺陷(如生长平台)的影响。这些区域在平面上形成规则的条纹图案，其特征尺寸为10到50美元\m$。条纹的方向相对于四方的(100)和(010)方向是固定的，但在相变过程中热循环时可以改变90美元。这种结构域模式可能对砷化铁的本征无序和各向异性有深远的影响。
The parent compounds of recently discovered iron-arsenide superconductors, $A$Fe$_2$As$_2$ with alkaline earth $A$=Ca, Sr, Ba, undergo simultaneous structural and magnetic phase transitions at a temperature $T_{SM}$. Using a combination of polarized light microscopy and spatially resolved high-energy synchrotron X-ray diffraction we show that the orthorhombic distortion leads to the formation of 45$^o$-type structural domains in all parent compounds. Domains penetrate through the sample thickness in the $c$- direction and are not affected by crystal defects such as growth terraces. The domains form regular stripe patterns in the plane with a characteristic dimension of 10 to 50 $\mu m$. The direction of the stripes is fixed with respect to the tetragonal (100) and (010) directions but can change by 90$^o$ on thermal cycling through the transition. This domain pattern may have profound implications for intrinsic disorder and anisotropy of iron arsenides.