Nethwewala Aditi, Lee Hyungwoo, Li Jianan, Briggeman Megan, Pai Yun-Yi, Eom Kitae, Eom Chang-Beom, Irvin Patrick, Levy Jeremy
Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
Pittsburgh Quantum Institute, Pittsburgh, PA, 15260, USA.
Nat Commun. 2023 Nov 23;14(1):7657. doi: 10.1038/s41467-023-43539-x.
Strongly correlated electronic systems exhibit a wealth of unconventional behavior stemming from strong electron-electron interactions. The LaAlO/SrTiO (LAO/STO) heterostructure supports rich and varied low-temperature transport characteristics including low-density superconductivity, and electron pairing without superconductivity for which the microscopic origins is still not understood. LAO/STO also exhibits inexplicable signatures of electronic nematicity via nonlinear and anomalous Hall effects. Nanoscale control over the conductivity of the LAO/STO interface enables mesoscopic experiments that can probe these effects and address their microscopic origins. Here we report a direct correlation between electron pairing without superconductivity, anomalous Hall effect and electronic nematicity in quasi-1D ballistic nanoscale LAO/STO Hall crosses. The characteristic magnetic field at which the Hall coefficient changes directly coincides with the depairing of non-superconducting pairs showing a strong correlation between the two distinct phenomena. Angle-dependent Hall measurements further reveal an onset of electronic nematicity that again coincides with the electron pairing transition, unveiling a rotational symmetry breaking due to the transition from paired to unpaired phases at the interface. The results presented here highlights the influence of preformed electron pairs on the transport properties of LAO/STO and provide evidence of the elusive pairing "glue" that gives rise to electron pairing in SrTiO-based systems.
强关联电子系统展现出源自强电子 - 电子相互作用的丰富非常规行为。LaAlO₃/SrTiO₃（LAO/STO）异质结构具有丰富多样的低温输运特性，包括低密度超导性以及电子配对但无超导性的现象，其微观起源仍不明确。LAO/STO还通过非线性和反常霍尔效应展现出难以解释的电子向列相特征。对LAO/STO界面电导率的纳米尺度控制使得介观实验能够探测这些效应并探究其微观起源。在此，我们报道了在准一维弹道纳米尺度LAO/STO霍尔交叉结构中，无超导性的电子配对、反常霍尔效应与电子向列相之间的直接关联。霍尔系数发生变化时的特征磁场与非超导对的解配对直接吻合，表明这两种不同现象之间存在强关联。角度依赖的霍尔测量进一步揭示了电子向列相的起始，这同样与电子配对转变相吻合，揭示了由于界面处从配对相到非配对相的转变而导致的旋转对称性破缺。此处呈现的结果突出了预形成的电子对对LAO/STO输运性质的影响，并为在基于SrTiO₃的系统中产生电子配对的难以捉摸的配对“胶水”提供了证据。
