Mallik Srijani, Ménard Gerbold C, Saïz Guilhem, Gilmutdinov Ildar, Vignolles David, Proust Cyril, Gloter Alexandre, Bergeal Nicolas, Gabay Marc, Bibes Manuel
Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 1 Avenue Augustin Fresnel, 91767 Palaiseau, France.
Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, PSL University, CNRS, Sorbonne Université, 75005 Paris, France.
Nano Lett. 2022 Jan 12;22(1):65-72. doi: 10.1021/acs.nanolett.1c03198. Epub 2021 Dec 16.
Quantum materials harbor a cornucopia of exotic transport phenomena challenging our understanding of condensed matter. Among these, a giant, nonsaturating linear magnetoresistance (MR) has been reported in various systems, from Weyl semimetals to topological insulators. Its origin is often ascribed to unusual band structure effects, but it may also be caused by extrinsic sample disorder. Here, we report a very large linear MR in a SrTiO two-dimensional electron gas and, by combining transport measurements with electron spectromicroscopy, show that it is caused by nanoscale inhomogeneities that are self-organized during sample growth. Our data also reveal semiclassical Sondheimer oscillations arising from interferences between helicoidal electron trajectories, from which we determine the 2DEG thickness. Our results bring insight into the origin of linear MR in quantum materials, expand the range of functionalities of oxide 2DEGs, and suggest exciting routes to explore the interaction of linear MR with features like Rashba spin-orbit coupling.
量子材料蕴含着大量奇异的输运现象，挑战着我们对凝聚态物质的理解。其中，从外尔半金属到拓扑绝缘体等各种体系中都报道了巨大的、非饱和的线性磁电阻（MR）。其起源通常归因于异常的能带结构效应，但也可能由外在的样品无序引起。在此，我们报道了SrTiO二维电子气中非常大的线性磁电阻，并通过将输运测量与电子能谱显微镜相结合，表明它是由样品生长过程中自组织形成的纳米尺度不均匀性引起的。我们的数据还揭示了螺旋电子轨迹之间干涉产生的半经典桑德海默振荡，据此我们确定了二维电子气的厚度。我们的结果为量子材料中线性磁电阻的起源提供了见解扩展了氧化物二维电子气的功能范围，并为探索线性磁电阻与诸如 Rashba 自旋轨道耦合等特性的相互作用指明了令人兴奋的途径。
