Porter Zach, Need Ryan F, Ahadi Kaveh, Zhao Yang, Xu Zhijun, Kirby Brian J, Lynn Jeffrey W, Stemmer Susanne, Wilson Stephen D
Materials Department, University of California, Santa Barbara, California 93106, USA.
Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611, USA.
Phys Rev Mater. 2020 May;4(5). doi: 10.1103/PhysRevMaterials.4.054411.
We report on the evolution of the average and depth-dependent magnetic order in thin-film samples of biaxially stressed and electron-doped EuTiO for samples across a doping range < 0.1 to 7.8 × 10 cm. Under an applied in-plane magnetic field, the -type antiferromagnetic ground state undergoes a continuous spin-flop phase transition into in-plane, field-polarized ferromagnetism. The critical field for ferromagnetism slightly decreases with an increasing number of free carriers, yet the field evolution of the spin-flop transition is qualitatively similar across the doping range. Unexpectedly, we observe interfacial ferromagnetism with saturated Eu moments at the substrate interface at low fields preceding ferromagnetic saturation throughout the bulk of the degenerate semiconductor film. We discuss the implications of these findings for the unusual magnetotransport properties of this compound.
我们报告了双轴应力和电子掺杂的EuTiO薄膜样品在掺杂范围从<0.1到7.8×10 cm的平均和深度相关磁序的演变。在施加的面内磁场下， -型反铁磁基态经历连续的自旋翻转相变，转变为面内场极化铁磁性。铁磁性的临界场随着自由载流子数量的增加而略有降低，但自旋翻转转变的场演变在整个掺杂范围内定性相似。出乎意料的是，在简并半导体薄膜整体达到铁磁饱和之前，我们在低场下观察到在衬底界面处具有饱和Eu磁矩的界面铁磁性。我们讨论了这些发现对该化合物异常磁输运性质的影响。
