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arXiv · 1505.05881

Structural and magnetic phase transitions in Ca$_{0.73}$La$_{0.27}$FeAs$_2$ with electron overdoped FeAs layers

Shan Jiang·Chang Liu·Huibo Cao·Turan Birol·Jared M. Allred·Wei Tian·Lian Liu·Kyuil Cho·Matthew J. Krogstad·Jie Ma·Keith M. Taddei·Makariy A. Tanatar·Moritz Hoesch·Ruslan Prozorov·Stephan Rosenkranz·Yasutomo J. Uemura·Gabriel Kotliar·Ni Ni
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Abstract

We report a study of the Ca$_{0.73}$La$_{0.27}$FeAs$_2$ single crystals. We unravel a monoclinic to triclinic phase transition at 58 K, and a paramagnetic to stripe antiferromagnetic (AFM) phase transition at 54 K, below which spins order 45$^\circ$ away from the stripe direction. Furthermore, we demonstrate this material is substantially structurally untwinned at ambient pressure with the formation of spin rotation walls (S-walls). Finally, in addition to the central-hole and corner-electron Fermi pockets usually appearing in Fe pnictide superconductors, angle-resolved photoemission (ARPES) measurements resolve a Fermiology where an extra electron pocket of mainly As chain character exists at the Brillouin zone edge.

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Shan Jiang, Chang Liu, Huibo Cao, Turan Birol, Jared M. Allred, Wei Tian, Lian Liu, Kyuil Cho, Matthew J. Krogstad, Jie Ma, Keith M. Taddei, Makariy A. Tanatar, Moritz Hoesch, Ruslan Prozorov, Stephan Rosenkranz, Yasutomo J. Uemura, Gabriel Kotliar, Ni Ni. 2016-03-14. Structural and magnetic phase transitions in Ca$_{0.73}$La$_{0.27}$FeAs$_2$ with electron overdoped FeAs layers. https://doi.org/10.1103/physrevb.93.054522

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