Static and dynamic signatures of anisotropic electronic phase separation in La2/3Ca1/3MnO3 thin films under anisotropic strain
Static and dynamic signatures of anisotropic electronic phase separation in La2/3Ca1/3MnO3 thin films under anisotropic strain
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DOI：
10.1103/physrevb.97.214428
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发表时间：
2018-06
影响因子：
3.7
通讯作者：
Longqian Hu;Liuqi Yu;P. Xiong;Xiaolei Wang;Jianhua Zhao;Lingfei Wang;Zhen Huang;Wenbin Wu
中科院分区：
文献类型：
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作者：
Longqian Hu;Liuqi Yu;P. Xiong;Xiaolei Wang;Jianhua Zhao;Lingfei Wang;Zhen Huang;Wenbin Wu
通过静态磁输运和动态弛豫测量，研究了最佳掺杂的La 2/3Ca 1/3 MnO 3（LCMO）薄膜在不同程度的各向异性应变下的电子相分离（EPS）.采用脉冲激光沉积法在（001）NdGaO 3（NGO）基片上同时生长了3层LCMO薄膜，并在780 ℃的氧气气氛中进行了不同时间的退火处理。随着退火时间的增加，薄膜沿两个正交的面内方向产生明显的沿着相反符号的应变。沿两个正交方向沿着同时测量静态温度依赖电阻率R（T）。随着退火时间的增加，零场冷却和场冷却的R（T）都显示出显着的增加，这表明应变触发的EPS和反铁磁绝缘（AFI）相在铁磁金属（FMM）基态的外观。同时，R（T）沿着拉伸应变[010]方向逐渐大于沿沿着压缩应变[100]方向。增强的电阻率各向异性表明EPS的特征在于具有沿[100]的优选取向沿着的相分离的FMM实体，这可能是由于在增强的各向异性应变下MnO 6八面体的协同变形和旋转/倾斜。各向异性EPS也可以通过外部磁场进行调谐。在几个固定温度下的场循环期间，AFI相在高场熔化并在低场恢复，导致高达104的比率的急剧电阻变化。此外，电阻率被发现表现出类似玻璃的行为，在相分离状态下弛豫。拟合数据的唯象模型，由此产生的电阻粘度和特征弛豫时间被发现随温度的变化，表现出密切的相关性与静态测量的EPS状态。
The electronic phase separation (EPS) of optimally doped La2/3Ca1/3MnO3 (LCMO) thin films under various degrees of anisotropic strain is investigated by static magnetotransport and dynamic relaxation measurements. Three LCMO films were grown simultaneously on (001) NdGaO3 (NGO) substrates by pulsed laser deposition, and then post-growth annealed at 780 oC in O2 for different durations of time. With increasing annealing time, the films developed significant strains of opposite signs along the two orthogonal in-plane directions. The static temperature-dependent resistivity, R(T), was measured simultaneously along the two orthogonal directions. With increasing annealing time, both zero-field-cooled and field-cooled R(T) show significant increases, suggesting strain-triggered EPS and appearance of antiferromagnetic insulating (AFI) phases in a ferromagnetic metallic (FMM) ground state. Meanwhile, R(T) along the tensile-strained [010] direction becomes progressively larger than that along the compressive-strained [100]. The enhanced resistivity anisotropy indicates that the EPS is characterized by phase-separated FMM entities with a preferred orientation along [100], possibly due to the cooperative deformation and rotation/tilting of the MnO6 octahedra under the enhanced anisotropic strain. The anisotropic EPS can also be tuned by an external magnetic field. During a field-cycle at several fixed temperatures, the AFI phases are melted at high fields and recovered at low fields, resulting in sharp resistance changes of the ratio as high as 104. Furthermore, the resistivity was found to exhibit glass-like behavior, relaxing logarithmically in the phase-separated states. Fitting the data to a phenomenological model, the resulting resistive viscosity and characteristic relaxation time are found to evolve with temperature, showing a close correlation with the static measurements in the EPS states.