Microscopic phase diagram of LaFeAsO single crystals under pressure
Microscopic phase diagram of LaFeAsO single crystals under pressure
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DOI：
10.1103/physrevb.98.174510
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发表时间：
2018-11-26
影响因子：
3.7
通讯作者：
Alp, E. Ercan
中科院分区：
文献类型：
--
作者：
Materne, Philipp;Bi, Wenli;Alp, E. Ercan
我们通过同步加速器穆斯堡尔光谱法在高达 7.5 GPa 和低至 13 K 的压力下研究了 LaFeAsO 单晶，并提供了微观相图。我们发现随着压力的增加，超精细磁场会持续受到抑制，并且在大约 7.5 GPa 时它完全消失，这与多晶样品中的行为形成鲜明对比，多晶样品中磁序在大约 20 GPa 时消失。多晶样品的不同行为可能是由于砷空位造成的。我们的结果与密度泛函理论计算定性一致，发现磁矩随着压力的增加而减少。我们发现，在不同的样品中，磁相变温度以及低温超精细磁场随着晶胞体积的增加而降低。
We investigated a LaFeAsO single crystal by means of synchrotron Mossbauer spectroscopy under pressure up to 7.5 GPa and down to 13 K and provide a microscopic phase diagram. We found a continuous suppression of the magnetic hyperfine field with increasing pressure, and it completely vanishes at similar to 7.5 GPa, which is in contrast to the behavior in polycrystalline samples where the magnetic order vanishes at similar to 20 GPa. The different behaviors of the polycrystalline samples might be due to As vacancies. Our results are in qualitative agreement with density functional theory calculations where a reduction of the magnetic moment with increasing pressure was found. We found that among different samples the magnetic phase-transition temperature as well as the low-temperature magnetic hyperfine field decrease with increasing unit-cell volume.