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arXiv · 1906.00509

An XMCD study of magnetism and valence state in iron-substituted strontium titanate

Astera S. Tang·Jonathan Pelliciari·Qi Song·Qian Song·Shuai Ning·John W. Freeland·Riccardo Comin·Caroline A. Ross
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Abstract

Room temperature ferromagnetism was characterized for thin films of SrTi$_{0.6}$Fe$_{0.4}$O$_{3-{\delta}}$ grown by pulsed laser deposition on SrTiO$_{3}$ and Si substrates under different oxygen pressures and after annealing under oxygen and vacuum conditions. X-ray magnetic circular dichroism demonstrated that the magnetization originated from Fe$^{2+}$ cations, whereas Fe$^{3+}$ and Ti$^{4+}$ did not contribute. Films with the highest magnetic moment (0.8 {\mu}B per Fe) had the highest measured Fe$^{2+}$:Fe${^3+}$ ratio of 0.1 corresponding to the largest concentration of oxygen vacancies ({\delta} = 0.19). Post-growth annealing treatments under oxidizing and reducing conditions demonstrated quenching and partial recovery of magnetism respectively, and a change in Fe valence states. The study elucidates the microscopic origin of magnetism in highly Fe-substituted SrTi$_{1-x}$Fe$_x$O$_{3-{\delta}}$ perovskite oxides and demonstrates that the magnetic moment, which correlates with the relative content of Fe$^{2+}$ and Fe$^{3+}$, can be controlled via the oxygen content, either during growth or by post-growth annealing.

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Astera S. Tang, Jonathan Pelliciari, Qi Song, Qian Song, Shuai Ning, John W. Freeland, Riccardo Comin, Caroline A. Ross. 2019-06-03. An XMCD study of magnetism and valence state in iron-substituted strontium titanate. https://doi.org/10.1103/physrevmaterials.3.054408

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