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arXiv · 1808.06654

Microscopic phase diagram of LaFeAsO single crystals under pressure

Philipp Materne·Wenli Bi·Jiyong Zhao·Michael Y. Hu·Rhea Kappenberger·Sabine Wurmehl·Saicharan Aswartham·Bernd Büchner·E. Ercan Alp
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Abstract

We investigated LaFeAsO single crystals by means of synchrotron M\"ossbauer spectroscopy under pressures 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 $\sim$ 7.5 GPa which is in contrast to the behavior in polycrystalline samples where the magnetic order vanishes at $\sim$ 20 GPa. The different behavior 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 at ambient pressure the magnetic phase transition temperature as well as the low-temperature magnetic hyperfine field decrease with increasing unit cell volume.

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Philipp Materne, Wenli Bi, Jiyong Zhao, Michael Y. Hu, Rhea Kappenberger, Sabine Wurmehl, Saicharan Aswartham, Bernd Büchner, E. Ercan Alp. 2018-08-20. Microscopic phase diagram of LaFeAsO single crystals under pressure. https://doi.org/10.1103/physrevb.98.174510

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