Critical Behavior of the (111)‐Oriented LaCoO3/SrTiO3 Thin Film
Critical Behavior of the (111)‐Oriented LaCoO3/SrTiO3 Thin Film
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(111) 取向 LaCoO3/SrTiO3 薄膜的临界行为
DOI：
10.1002/pssb.202100424
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Hao Yang
中科院分区：
文献类型：
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作者：
Hao Liu;Jiyu Fan;Jun Zhao;F. Qian;Yan Zhu;Chunlan Ma;A. Rahman;Lei Zhang;Hao Yang
除了不同衬底对外延薄膜晶格常数失配的影响外，同一衬底不同晶向也会影响外延薄膜的性能。在此，（111）取向的SrTiO 3（STO）衬底用于制造LaCoO 3（LCO）外延薄膜，而不是更常见的（001）取向的STO衬底。在50 K附近经历一次顺磁-铁磁相变。这一相变与先前观察到的（001）-LCO/STO相似，但居里温度（Tc）明显低于先前报道的80 K。为了研究Tc的降低并进一步了解相变，进行了薄膜的临界行为分析。通过重建修正的Arrott图，确定了临界指数β = 1.591（3）和γ = 0.937（1），并用Widom标度关系证实了这些指数的可靠性。使用重整化群理论方法，发现薄膜具有空间维度d = 2和自旋维度n = 1的长程磁相互作用，并且磁交换相互作用衰减J（r）<$r − 2.4473。
Apart from the impact of different substrates on epitaxial thin films due to lattice constant mismatches, the properties of epitaxial thin films are also influenced by the same substrates with different crystal orientations. Herein, the (111)‐oriented SrTiO3 (STO) substrates are used to fabricate the LaCoO3 (LCO) epitaxial thin films rather than the more common (001)‐oriented STO substrates. It undergoes one paramagnetic–ferromagnetic phase transition around 50 K. This phase transition is similar to the previously observed for (001)‐LCO/STO, but the Curie temperature (T c) is significantly lower than the previously reported 80 K. To investigate the decrease of T c and gain further insight into the phase transition, the critical behavior analysis of thin film is performed. The critical exponents are determined to be β = 1.591(3) and γ = 0.937(1) by reconstructing a modified Arrott plot, and the reliability of these exponents is confirmed by the Widom scaling relation. Using the renormalization group theory approach, it is discovered that the film has a long‐range magnetic interaction with space dimensionality d = 2 and spin dimensionality n = 1, and the magnetic exchange interaction decays J ( r ) ≈ r − 2.4473 .