Department of Applied Physics, Stanford University, Stanford, CA 94305, USA.
Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.
Science. 2020 Apr 3;368(6486):71-76. doi: 10.1126/science.aax9753. Epub 2020 Apr 2.
A defining feature of emergent phenomena in complex oxides is the competition and cooperation between ground states. In manganites, the balance between metallic and insulating phases can be tuned by the lattice; extending the range of lattice control would enhance the ability to access other phases. We stabilized uniform extreme tensile strain in nanoscale LaCaMnO membranes, exceeding 8% uniaxially and 5% biaxially. Uniaxial and biaxial strain suppresses the ferromagnetic metal at distinctly different strain values, inducing an insulator that can be extinguished by a magnetic field. Electronic structure calculations indicate that the insulator consists of charge-ordered Mn and Mn with staggered strain-enhanced Jahn-Teller distortions within the plane. This highly tunable strained membrane approach provides a broad opportunity to design and manipulate correlated electron states.
复杂氧化物中突现现象的一个显著特点是基态之间的竞争与合作。在锰氧化物中，通过晶格可以调节金属相和绝缘相之间的平衡；扩展晶格控制范围将提高进入其他相的能力。我们在纳米级 LaCaMnO 薄膜中稳定了均匀的极端拉伸应变，超过 8%的单轴应变和 5%的双轴应变。单轴和双轴应变在明显不同的应变值下抑制铁磁金属，诱导出一种可以被磁场熄灭的绝缘相。电子结构计算表明，该绝缘相由电荷有序的 Mn 和 Mn 组成，在平面内存在交错应变增强的 Jahn-Teller 畸变。这种高度可调的应变膜方法为设计和控制相关电子态提供了广泛的机会。
