Epitaxy-distorted spin-orbit Mott insulator in Sr 2 IrO 4 thin films
Epitaxy-distorted spin-orbit Mott insulator in Sr 2 IrO 4 thin films
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DOI：
10.1103/physrevb.87.085121
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发表时间：
2012-09
影响因子：
3.7
通讯作者：
C. Serrao;Jian Liu;J. Heron;G. Singh-Bhalla;A. Yadav;S. Suresha;R. J. Paull;D. Yi;J. Chu;M. Trassin;A. Vishwanath;E. Arenholz;C. Frontera;J. vZelezn'y;T. Jungwirth;X. Marti;R. Ramesh
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文献类型：
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作者：
C. Serrao;Jian Liu;J. Heron;G. Singh-Bhalla;A. Yadav;S. Suresha;R. J. Paull;D. Yi;J. Chu;M. Trassin;A. Vishwanath;E. Arenholz;C. Frontera;J. vZelezn'y;T. Jungwirth;X. Marti;R. Ramesh
在SrTiO${}_{3}$（001）衬底上生长出了高质量的${J}_{\ mathm {eff}}$ $=$ 1/2 Mott绝缘体Sr${}_{2}$IrO${}_{4}$的外延薄膜，其面内拉伸应变增大。将面内拉伸应变增加到\ensuremath{\sim}0.3$%$时，可以使$c$/$a$四边形降低1.2$%$。x射线吸收光谱检测到，随着平面内拉伸应变的增加，局部电子结构的各向异性降低，线性二色性明显降低。虽然最松弛的薄膜显示出与先前报道的单晶体积测量一致的依赖性，但对于最薄和外延扭曲最严重的薄膜，电输运显示电荷间隙从200 meV减少到50 meV。我们认为正方性的减少在电子结构的变化中起主要作用，这反映在输运性质的变化上。我们的工作开启了利用外延应变作为自旋轨道Mott系统结构和功能操纵工具的可能性。
High-quality epitaxial thin films of ${J}_{\mathrm{eff}}$ $=$ 1/2 Mott insulator Sr${}_{2}$IrO${}_{4}$ with increasing in-plane tensile strain have been grown on top of SrTiO${}_{3}$(001) substrates. Increasing the in-plane tensile strain up to \ensuremath{\sim}0.3$%$ was observed to drop the $c$/$a$ tetragonality by 1.2$%$. X-ray absorption spectroscopy detected a strong reduction of the linear dichroism upon increasing in-plane tensile strain towards a reduced anisotropy in the local electronic structure. While the most relaxed thin film shows a consistent dependence with previously reported single crystal bulk measurements, electrical transport reveals a charge gap reduction from 200 meV down to 50 meV for the thinnest and most epitaxy-distorted film. We argue that the reduced tetragonality plays a major role in the change of the electronic structure, which is reflected in the change of the transport properties. Our work opens the possibility for exploiting epitaxial strain as a tool for both structural and functional manipulation of spin-orbit Mott systems.