Araujo C Moyses, Nagar Sandeep, Ramzan Muhammad, Shukla R, Jayakumar O D, Tyagi A K, Liu Yi-Sheng, Chen Jeng-Lung, Glans Per-Anders, Chang Chinglin, Blomqvist Andreas, Lizárraga Raquel, Holmström Erik, Belova Lyubov, Guo Jinghua, Ahuja Rajeev, Rao K V
Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120, Uppsala, Sweden.
Department of Materials Science, Tmfy-MSE, Royal Institute of Technology, SE100 44 Stockholm, Sweden.
Sci Rep. 2014 Apr 15;4:4686. doi: 10.1038/srep04686.
We report an unusual robust ferromagnetic order above room temperature upon amorphization of perovskite [YCrO3] in pulsed laser deposited thin films. This is contrary to the usual expected formation of a spin glass magnetic state in the resulting disordered structure. To understand the underlying physics of this phenomenon, we combine advanced spectroscopic techniques and first-principles calculations. We find that the observed order-disorder transformation is accompanied by an insulator-metal transition arising from a wide distribution of Cr-O-Cr bond angles and the consequent metallization through free carriers. Similar results also found in YbCrO3-films suggest that the observed phenomenon is more general and should, in principle, apply to a wider range of oxide systems. The ability to tailor ferromagnetic order above room temperature in oxide materials opens up many possibilities for novel technological applications of this counter intuitive effect.
我们报道了在脉冲激光沉积薄膜中钙钛矿[YCrO₃]非晶化后，在室温以上出现了异常强的铁磁有序。这与在所得无序结构中通常预期形成的自旋玻璃磁态相反。为了理解这一现象的潜在物理机制，我们结合了先进的光谱技术和第一性原理计算。我们发现，观察到的有序-无序转变伴随着由Cr-O-Cr键角的广泛分布引起的绝缘体-金属转变，以及随之而来的通过自由载流子的金属化。在YbCrO₃薄膜中也发现了类似结果，这表明观察到的现象更为普遍，原则上应适用于更广泛的氧化物体系。在氧化物材料中定制室温以上铁磁有序的能力为这种违反直觉的效应的新型技术应用开辟了许多可能性。
