Phases of Quasi-One-Dimensional Fractional Quantum (Anomalous) Hall - Superconductor Heterostructures
Max-Planck Institute for Solid State Research（马克斯·普朗克固体研究所）；University of Luxembourg（卢森堡大学）；Purdue University（普渡大学）；University of Wisconsin-Madison（威斯康星大学麦迪逊分校）
Steffen Bollmann, Andreas Haller, Jukka I. Väyrynen, Thomas L. Schmidt, Elio J. König
Motivated by recent observations of fractional Chern insulators (FCIs) in the vicinity of superconducting (SC) phases, we study fractional quantum (anomalous) Hall-superconductor heterostructures in the presence of $U(1)$ order-parameter fluctuations and particularly focus on the case of $ν= 2/3$ quantum Hall states leading to $\mathbb Z_3$ parafermions. We first employ a phenomenological field theory to qualitatively determine the phase diagram. Furthermore, we generalize a previously established alternating pattern of superconductor and tunneling regions, coupled to fractional quantum Hall edge states, to map the problem onto a topological Josephson junction chain involving lattice parafermions. Using density matrix renormalization group simulations, we establish a phase diagram composed of Mott insulating phases and two different Luttinger liquids whose fundamental excitations carry charges 2e and $2e/3$, respectively. In agreement with analytical considerations using conformal field theory, we numerically find transitions of Berezinskii-Kosterlitz-Thouless (BKT) type as well as a continuous $\mathbb Z_3 \times U(1)$ second-order phase transition characterized by central charge c = 9/5. We finally extract information about a possible ground state degeneracy and comment on the stability of parafermionic edge states in the presence of fluctuations. These theoretical foundations can be expected to be of practical importance for gate-defined FCI-SC heterostructures in moiré materials, in which broad superconducting transitions indicative of strong order parameter fluctuations were observed.
Anomalous Magnetoresistance by Breaking Ice Rule in Bi2Ir2O7/Dy2Ti2O7 Heterostructure
虽然几何受抑量子磁体以各种奇异的自旋态而闻名，这些自旋态对理解涌现现象以及实现革命性的量子技术具有极大的兴趣，但它们中的大多数必然是良好的绝缘体，难以与依赖于移动载流子的现代电路集成。将涨落和受抑时刻的激发转化为电子响应的巨大挑战是找到引入载流子的方法，这些载流子与局域自旋相互作用而不破坏自旋态。在这里，我们表明，通过设计一个Bi 2 Ir 2 O 7/Dy 2 Ti 2 O 7异质结构，在绝缘Dy 2 Ti 2 O 7的自旋冰规则的打破可以导致在Bi 2 Ir 2 O 7导电层，可以检测到异常磁阻的电荷响应。这些结果展示了一种新颖可行的界面方法，用于电子探测绝缘磁体中的奇异自旋态，为受抑量子磁体的金属化奠定了蓝图。
Significant Unconventional Anomalous Hall Effect in Heavy Metal/Antiferromagnetic Insulator Heterostructures
反常霍尔效应（AHE）是一种量子相干输运现象，通常在高温下由于热退相而消失。因此，令人困惑的是，AHE可以生存在重金属（HM）/反铁磁（AFM）绝缘体（AFMI）异质结构在高温下，但在低温下消失。在本文中，我们报告了一个非常规的高温AHE在HM/AFMI只观察到附近的原子力显微镜的Néel温度，与大的异常霍尔电阻率高达40 n $Ω$ cm。这种机制是由于出现了一个非共线的AFM自旋织构与非零净拓扑电荷。原子自旋动力学模拟表明，这种独特的自旋织构可以通过共线AFM交换耦合、界面Dyzaloshinski-Moriya相互作用、热涨落和偏置磁场之间的微妙相互作用来稳定。
Symmetry-engineered and electrically tunable in-plane anomalous Hall effect in oxide heterostructures
Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China（合肥微尺度物质科学国家研究中心，中国科学技术大学）；Department of Physics, University of Science and Technology of China（中国科学技术大学物理学院）；Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences（中国科学院合肥物质科学研究院固体物理研究所材料物理重点实验室）；School of Physics, Northwest University（西北大学物理学院）；Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences（中国科学院强磁场科学中心极端条件凝聚态物理安徽省重点实验室）
The effect of inserted NiO layer on spin-Hall magnetoresistance in Pt/NiO/YIG heterostructures
利用自旋霍尔磁电阻（SMR）研究了Pt/NiO/Y $_3$ Fe $_5$ O $_{12}$（Pt/NiO/YIG）异质结中反铁磁绝缘层（AFMI）的自旋电流输运.通过插入AFMI NiO层，SMR通过将温度降低到NiO的反铁磁有序状态而显著降低，这意味着AFM有序阻止而不是促进自旋电流输运。另一方面，YIG对Pt磁矩的磁邻近效应（MPE）与Pt中的自旋霍尔效应（SHE）纠缠在一起，可以有效地屏蔽这种效应，通过NiO的插入可以得到纯SMR。与其他反铁磁金属（AFM）或非铁磁金属（NM）相比，NiO的插入具有有效阻挡MPE和将自旋电流从Pt传输到YIG的双重作用。
