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arXiv · 2409.07595

Low temperature state in strontium titanate microcrystals using in situ multi-reflection Bragg coherent X-ray diffraction imaging

David Yang·Ana F. Suzana·Longlong Wu·Sung Soo Ha·Sungwook Choi·Hieu Minh Ngo·Muhammad Mahmood Nawaz·Hyunjung Kim·Jialun Liu·Daniel Treuherz·Nan Zhang·Zheyi An·Gareth Nisbet·Daniel G. Porter·Ian K. Robinson
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Abstract

Strontium titanate is a classic quantum paraelectric oxide material that has been widely studied in bulk and thin films. It exhibits a well-known cubic-to-tetragonal antiferrodistortive phase transition at 105 K, characterized by the rotation of oxygen octahedra. A possible second phase transition at lower temperature is suppressed by quantum fluctuations, preventing the onset of ferroelectric order. However, recent studies have shown that ferroelectric order can be established at low temperatures by inducing strain and other means. Here, we used in situ multi-reflection Bragg coherent x-ray diffraction imaging to measure the strain and rotation tensors for two strontium titanate microcrystals at low temperature. We observe strains induced by dislocations and inclusion-like impurities in the microcrystals. Based on radial magnitude plots, these strains increase in magnitude and spread as the temperature decreases. Pearson's correlation heat maps show a structural transition at 50 K, which could possibly be the formation of a low-temperature ferroelectric phase in the presence of strain. We do not observe any change in local strains associated with the tetragonal phase transition at 105 K.

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David Yang, Ana F. Suzana, Longlong Wu, Sung Soo Ha, Sungwook Choi, Hieu Minh Ngo, Muhammad Mahmood Nawaz, Hyunjung Kim, Jialun Liu, Daniel Treuherz, Nan Zhang, Zheyi An, Gareth Nisbet, Daniel G. Porter, Ian K. Robinson. 2025-01-24. Low temperature state in strontium titanate microcrystals using in situ multi-reflection Bragg coherent X-ray diffraction imaging. https://doi.org/10.1103/physrevb.111.024107

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