Pruneda J M, Ferrari V, Rurali R, Littlewood P B, Spaldin N A, Artacho Emilio
Department of Physics, University of California, Berkeley, California 94720, USA.
Phys Rev Lett. 2007 Nov 30;99(22):226101. doi: 10.1103/PhysRevLett.99.226101. Epub 2007 Nov 26.
We present the structure of the fully relaxed (001) surface of the half-metallic manganite La0.7Sr0.3MnO3, calculated using density functional theory. Two relevant ferroelastic order parameters are identified and characterized. The known tilting of the oxygen octahedra, which is present in the bulk phase, decreases towards the surface. A ferrodistortive Mn off-centering, triggered by the surface and not reported before, decays monotonically into the bulk. This distortion affects neither the half-metallicity nor the zero-temperature magnetization, but does change the effective spin-spin interactions, and thus the temperature dependence of the magnetic properties.
我们展示了利用密度泛函理论计算得到的半金属锰氧化物La0.7Sr0.3MnO3完全弛豫的(001)表面结构。确定并表征了两个相关的铁弹性序参量。体相中存在的氧八面体的已知倾斜向表面逐渐减小。一种由表面引发且此前未被报道的铁畸变锰原子偏心，向体相单调衰减。这种畸变既不影响半金属性也不影响零温磁化强度，但确实改变了有效的自旋-自旋相互作用，从而改变了磁性质的温度依赖性。
