Large polarons as key quasiparticles in SrTiO3 and SrTiO3-based heterostructures
Andrey Geondzhian, Alessia Sambri, Gabriella M. De Luca, Roberto Di Capua, Emiliano Di Gennaro, Davide Betto, Matteo Rossi, Ying Ying Peng, Roberto Fumagalli, N… 展开作者
Andrey Geondzhian, Alessia Sambri, Gabriella M. De Luca, Roberto Di Capua, Emiliano Di Gennaro, Davide Betto, Matteo Rossi, Ying Ying Peng, Roberto Fumagalli, Nicholas B. Brookes, Lucio Braicovich, Keith Gilmore, Giacomo Ghiringhelli, Marco Salluzzo
尽管SrTiO $_3$（STO）的结构简单，电子相关性低，但它具有与电荷输运相关的集体现象，并最终具有超导性，这些现象尚未得到充分解释。因此，需要更好地了解准粒子的性质，塑造STO的电子和导电性能。利用Ti L $_3$边缘共振非弹性X射线散射研究了体相STO和LaAlO $_{3}$ /SrTiO $_{3}$二维电子气（2DEG）的低能激发.在所有样品中，我们发现极化子的特征是强烈的$dd$ +声子激发，以及从绝缘到高导电STO单晶和异质结构时LO 3模式电子-声子耦合的减少。这两个结果都归因于大极化子自激极化的动态屏蔽，表明STO和基于STO的2DEG的低温物理由大极化子准粒子主导。
英文摘要：
Despite its simple structure and low degree of electronic correlation, SrTiO$_3$ (STO) features collective phenomena linked to charge transport and, ultimately, superconductivity, that are not yet fully explained. Thus, a better insight in the nature of the quasiparticles shaping the electronic and conduction properties of STO is needed. We studied the low energy excitations of bulk STO and of the LaAlO$_{3}$/SrTiO$_{3}$ two dimensional electron gas (2DEG) by Ti L$_3$ edge resonant inelastic x-ray scattering. In all samples, we find the hallmark of polarons in the form of intense $dd$+phonon excitations, and a decrease of the LO3-mode electron-phonon coupling when going from insulating to highly conducting STO single crystals and heterostructures. Both results are attributed to the dynamic screening of the large polaron self-induced polarization, showing that the low temperature physics of STO and STO-based 2DEGs is dominated by large polaron quasiparticles.
We consider dressing of excitonic properties by strongly correlated electrons in gate controlled twisted homo-bilayer heterostructures. The combined effect of the moiré potential and the Coulomb interaction supports the formation of different strongly correlated phases depending on the filling, including charge-ordered metals or incompressible insulators at integer occupation. The coupling between excitons and electrons results in a splitting of the excitonic resonance into an attractive and a repulsive polaron peak. Analyzing the properties of the exciton-polarons across the different phases …
Polarons are composite quasiparticles comprising electronic charge carriers taken together with the alterations they induce in surrounding condensed matter. Strong-coupling polarons form when electronic charge carriers become self-trapped: bound within potential wells stabilized by carriers presence. Distinctively, exciting these bound carriers generates broad absorption bands. Strong-coupling polarons are slow and massive since moving them requires atomic motion. Their transport differs qualitatively from that of conventional electronic charge carriers. Large (strong-coupling) polarons move c…
Purely electronic model for exciton-polaron formation in moiré heterostructures
Technical University of Munich（慕尼黑工业大学）；Munich Center for Quantum Science and Technology (MCQST)（慕尼黑量子科学与技术中心）；Joint Quantum Institute, University of Maryland（马里兰大学联合量子研究所）
The parity-preserving $U(1)\times U(1)$ massless QED$_3$ is proposed as a pristine graphene-like planar quantum electrodynamics model. The spectrum content, the degrees of freedom, spin, masses and charges of the quasiparticles (electron-polaron, hole-polaron, photon and Néel quasiparticles) which emerge from the model are discussed. The four-fold broken degeneracy of the Landau levels, similar as the one experimentally observed in pristine graphene submitted to high applied external magnetic fields, is obtained. Furthermore, the model exhibits zero-energy Landau level indicating a kind of ano…
Spectral Properties of Holstein and Breathing Polarons
我们用自洽玻恩近似计算了一维Holstein极化子和呼吸极化子的光谱性质。Holstein模型的电子-声子耦合是动量无关的，而呼吸耦合随声子动量单调增加。我们发现，对于线性或紧密结合的电子色散：i）对于相同的无量纲耦合值，呼吸极化子中小动量处的准粒子重整化要小得多，ii）呼吸极化子中小动量处的准粒子重整化随着声子频率而增加，这与Holstein模型中的情况不同，在Holstein模型中，准粒子重整化随着声子频率而减少，iii）在Holstein模型中，准粒子色散在等于声子频率w 0的激发能处显示扭结和小间隙，而在呼吸模型中，它显示两个间隙，一个在激发能w 0处，另一个在2 w 0处。这些差异有两个原因：第一，相关散射声子的动量随着极化子动量的增加而增加;第二，呼吸裸耦合是声子动量的增函数。这导致呼吸模型的有效的电子-声子耦合是总极化子动量的增函数，使得小动量极化子处于弱耦合区，而大动量极化子处于强耦合区。然而，如果自由电子色散具有被大动量分离的低能态，则第一个原因不成立，例如在更高维的系统中，在这种情况下，两个模型之间的差异变得不那么显著。
Polaron quasiparticles are formed when a mobile impurity is coupled to the elementary excitations of a many-particle background. In the field of ultracold atoms, the study of the associated impurity problem has attracted a growing interest over the last fifteen years. Polaron quasiparticle properties are essential to our understanding of a variety of paradigmatic quantum many-body systems realized in ultracold atomic gases and in the solid state, from imbalanced Bose-Fermi and Fermi-Fermi mixtures to fermionic Hubbard models. In this topical review, we focus on the so-called repulsive polaron …
Universität Heidelberg（海德堡大学）；University of Warsaw（华沙大学）；National University of Singapore（新加坡国立大学）；Max-Planck-Institut für Quantenoptik（马克斯·普朗克量子光学研究所）
Programmable Polaron Models and Tomography in Trapped-Ion Quantum Simulators
Institute for Theoretical Physics, ETH Zürich（苏黎世联邦理工学院理论物理研究所）；IBM Quantum, IBM Research – Zurich（IBM量子，IBM苏黎世研究中心）；Department of Physics and Astronomy and Smalley-Curl Institute, Rice University（莱斯大学天体物理学与天文系及Smalley-Curl研究所）；California Institute of Technology（加州理工学院）
Momentum average approximation for models with boson-modulated hopping: Role of closed loops in the dynamical generation of a finite quasiparticle mass
Dispersion of low-energy optical excitations in NiPS$_3$ explained by singlet polaron theory
Instituto de Física Rosario (CONICET) and Facultad de Ciencias Exactas, Ingeniería y Agrimensura, Universidad Nacional de Rosario（罗萨里奥物理研究所（阿根廷国家科学和技术研究委员会）及罗萨里奥国立大学精确科学、工程和测量学院）；Instituto de Nanociencia y Nanotecnología CNEA-CONICET, GAIDI, Centro Atómico Bariloche and Instituto Balseiro（CNEA-CONICET纳米科学与技术研究所、GAIDI、巴里洛切原子中心及巴尔塞罗研究所）；Physics Department, Northeastern University（东北大学物理系）
Interaction-driven spin polaron in itinerant flat-band ferromagnetism
National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University（南京大学固态微结构国家重点实验室和物理学院）；School of Physics, Nanjing University of Science and Technology（南京理工大学物理学院）；Jiangsu Physical Science Research Center（江苏省物理科学研究中心）；Collaborative Innovation Center of Advanced Microstructures, Nanjing University（南京大学先进微结构协同创新中心）；Jiangsu Key Laboratory of Quantum Information Science and Technology, Nanjing University（南京大学江苏省量子信息科学与技术重点实验室）
We report experimental and theoretical evidence of strong electron-plasmon interaction in n-doped single-layer MoS2. Angle-resolved photoemission spectroscopy (ARPES) measurements reveal the emergence of distinctive signatures of polaronic coupling in the electron spectral function. Calculations based on many-body perturbation theory illustrate that electronic coupling to two-dimensional (2D) carrier plasmons provides an exhaustive explanation of the experimental spectral features and their energies. These results constitute compelling evidence of the formation of plasmon-induced polaronic qua…
Emergent Weyl Nodes and Berry Curvature in Bose Polarons via $p$-Wave Feshbach Coupling
The University of Tokyo（东京大学）；RIKEN Nishina Center（理化学研究所西村中心）；Quark Nuclear Science Institute, The University of Tokyo（东京大学夸克核科学研究所）；Kochi University（高知大学）；The Open University of Japan（日本开放大学）
