scholarly journals Oxygen vacancy-driven orbital multichannel Kondo effect in Dirac nodal line metals IrO2 and RuO2

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Sheng-Shiuan Yeh ◽  
Ta-Kang Su ◽  
An-Shao Lien ◽  
Farzaneh Zamani ◽  
Johann Kroha ◽  
...  
Keyword(s):  
Kondo Effect ◽  
High Temperature Superconductivity ◽  
Topological States Of Matter ◽  
Nodal Line ◽  
Metallic State ◽  
Strong Electron ◽  
Quantum Matter ◽  
Kondo Physics ◽  
Topological States ◽  
Weak Coupling Theory

Abstract Strong electron correlations have long been recognized as driving the emergence of novel phases of matter. A well recognized example is high-temperature superconductivity which cannot be understood in terms of the standard weak-coupling theory. The exotic properties that accompany the formation of the two-channel Kondo (2CK) effect, including the emergence of an unconventional metallic state in the low-energy limit, also originate from strong electron interactions. Despite its paradigmatic role for the formation of non-standard metal behavior, the stringent conditions required for its emergence have made the observation of the nonmagnetic, orbital 2CK effect in real quantum materials difficult, if not impossible. We report the observation of orbital one- and two-channel Kondo physics in the symmetry-enforced Dirac nodal line (DNL) metals IrO2 and RuO2 nanowires and show that the symmetries that enforce the existence of DNLs also promote the formation of nonmagnetic Kondo correlations. Rutile oxide nanostructures thus form a versatile quantum matter platform to engineer and explore intrinsic, interacting topological states of matter.

scholarly journals Kondo physics in antiferromagnetic Weyl semimetal Mn3+xSn1−x films

2020 ◽  
Vol 6 (35) ◽  
pp. eabc1977
Author(s):  
Durga Khadka ◽  
T. R. Thapaliya ◽  
Sebastian Hurtado Parra ◽  
Xingyue Han ◽  
Jiajia Wen ◽  
...  
Keyword(s):  
Kondo Effect ◽  
Energy Gap ◽  
Strongly Correlated ◽  
Strong Correlations ◽  
Strong Electron ◽  
Experimental Systems ◽  
Weyl Semimetal ◽  
Hall Effects ◽  
Kondo Physics ◽  
Gap Opening

Topology and strong electron correlations are crucial ingredients in emerging quantum materials, yet their intersection in experimental systems has been relatively limited to date. Strongly correlated Weyl semimetals, particularly when magnetism is incorporated, offer a unique and fertile platform to explore emergent phenomena in novel topological matter and topological spintronics. The antiferromagnetic Weyl semimetal Mn3Sn exhibits many exotic physical properties such as a large spontaneous Hall effect and has recently attracted intense interest. In this work, we report synthesis of epitaxial Mn3+xSn1−x films with greatly extended compositional range in comparison with that of bulk samples. As Sn atoms are replaced by magnetic Mn atoms, the Kondo effect, which is a celebrated example of strong correlations, emerges, develops coherence, and induces a hybridization energy gap. The magnetic doping and gap opening lead to rich extraordinary properties, as exemplified by the prominent DC Hall effects and resonance-enhanced terahertz Faraday rotation.

scholarly journals Towards the manipulation of topological states of matter: a perspective from electron transport

2018 ◽  
Vol 63 (9) ◽  
pp. 580-594 ◽  
Author(s):  
Cheng Zhang ◽  
Hai-Zhou Lu ◽  
Shun-Qing Shen ◽  
Yong P. Chen ◽  
Faxian Xiu
Keyword(s):  
Electron Transport ◽  
Topological States Of Matter ◽  
Topological States

scholarly journals Topological transitions in an oscillatory driven liquid crystal cell

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Marcel G. Clerc ◽  
Michał Kowalczyk ◽  
Valeska Zambra
Keyword(s):  
Liquid Crystal ◽  
Topological States Of Matter ◽  
Low Frequency ◽  
Vortex State ◽  
Liquid Crystal Cell ◽  
Topological Transition ◽  
Exotic States ◽  
Crystal Cell ◽  
Topological States ◽  
Topological Transitions

Abstract Matter under different equilibrium conditions of pressure and temperature exhibits different states such as solid, liquid, gas, and plasma. Exotic states of matter, such as Bose–Einstein condensates, superfluidity, chiral magnets, superconductivity, and liquid crystalline blue phases are observed in thermodynamic equilibrium. Rather than being a result of an aggregation of matter, their emergence is due to a change of a topological state of the system. These topological states can persist out of thermodynamics equilibrium. Here we investigate topological states of matter in a system with injection and dissipation of energy by means of oscillatory forcing. In an experiment involving a liquid crystal cell under the influence of a low-frequency oscillatory electric field, we observe a transition from a non-vortex state to a state in which vortices persist, topological transition. Depending on the period and the type of the forcing, the vortices self-organise, forming square lattices, glassy states, and disordered vortex structures. The bifurcation diagram is characterised experimentally. A continuous topological transition is observed for the sawtooth and square forcings. The scenario changes dramatically for sinusoidal forcing where the topological transition is discontinuous, which is accompanied by serial transitions between square and glassy vortex lattices. Based on a stochastic amplitude equation, we recognise the origin of the transition as the balance between stochastic creation and deterministic annihilation of vortices. Numerical simulations show topological transitions and the emergence of square vortex lattice. Our results show that the matter maintained out of equilibrium by means of the temporal modulation of parameters can exhibit exotic states.

scholarly journals Symmetry-protected hierarchy of anomalous multipole topological band gaps in nonsymmorphic metacrystals

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiujuan Zhang ◽  
Zhi-Kang Lin ◽  
Hai-Xiao Wang ◽  
Zhan Xiong ◽  
Yuan Tian ◽  
...  
Keyword(s):  
Band Gap ◽  
Topological States Of Matter ◽  
Quantum Spin ◽  
Band Gaps ◽  
Quantum Spin Hall Effect ◽  
Classical Systems ◽  
Topological Materials ◽  
And Topology ◽  
Topological States ◽  
Symmetry Protected

AbstractSymmetry and topology are two fundamental aspects of many quantum states of matter. Recently new topological materials, higher-order topological insulators, were discovered, featuring bulk–edge–corner correspondence that goes beyond the conventional topological paradigms. Here we discover experimentally that the nonsymmorphic p4g acoustic metacrystals host a symmetry-protected hierarchy of topological multipoles: the lowest band gap has a quantized Wannier dipole and can mimic the quantum spin Hall effect, whereas the second band gap exhibits quadrupole topology with anomalous Wannier bands. Such a topological hierarchy allows us to observe experimentally distinct, multiplexed topological phenomena and to reveal a topological transition triggered by the geometry transition from the p4g group to the C4v group, which demonstrates elegantly the fundamental interplay between symmetry and topology. Our study demonstrates that classical systems with controllable geometry can serve as powerful simulators for the discovery of novel topological states of matter and their phase transitions.

Novel topological states of nodal points and nodal rings in 2D planar octagon TiB4

Nanoscale ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 3194-3200
Author(s):  
Weizhen Meng ◽  
Wei Liu ◽  
Xiaoming Zhang ◽  
Ying Liu ◽  
Xuefang Dai ◽  
...  
Keyword(s):  
2D Materials ◽  
Topological States Of Matter ◽  
Two Dimensional ◽  
Nodal Points ◽  
Potential Applications ◽  
Topological States

Topological states of matter in two-dimensional (2D) materials have received increasing attention due to their potential applications in nanoscale spintronics.

scholarly journals GRAPHENE: JUNCTIONS AND STM SPECTRA

2012 ◽  
Vol 26 (21) ◽  
pp. 1242002 ◽  
Author(s):  
M. MAITI ◽  
K. SAHA ◽  
K. SENGUPTA
Keyword(s):  
Gate Voltage ◽  
Crucial Role ◽  
Kondo Effect ◽  
Experimental Studies ◽  
Low Energy ◽  
Scanning Tunneling ◽  
Magnetic Impurities ◽  
Tunneling Conductance ◽  
Kondo Physics ◽  
Barrier Region

The presence of low-energy Dirac-like quasiparticles is one of the central features responsible for plethora of recent theoretical and experimental studies on graphene. In this review, we focus on the effect of the Dirac nature of these quasiparticles on two separate aspects. The first of these involves transport across superconducting graphene junctions with barriers of thickness d and arbitrary gate voltages V0 applied across the barrier region. The second aspect involves study of the presence of localized magnetic impurities in graphene in which we discuss the unconventional nature of Kondo physics in graphene and the tunablity of Kondo effect with a gate voltage. We also chart out the nature of scanning tunneling conductance spectra for both doped and undoped graphene in the presence of impurities and discuss the effect of Dirac nature of graphene quasiparticles on such spectra. In particular, we provide a detailed analysis of the phenomenon that that the position of the impurity in the graphene matrix plays a crucial role in determining the nature of the STM specta.

scholarly journals Surface Kondo effect and non-trivial metallic state of the Kondo insulator YbB12

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Kenta Hagiwara ◽  
Yoshiyuki Ohtsubo ◽  
Masaharu Matsunami ◽  
Shin-ichiro Ideta ◽  
Kiyohisa Tanaka ◽  
...  
Keyword(s):  
Kondo Effect ◽  
Metallic State ◽  
Kondo Insulator

scholarly journals Tensor Monopoles in superconducting systems

Quantum ◽  
2021 ◽  
Vol 5 ◽  
pp. 601
Author(s):  
H. Weisbrich ◽  
M. Bestler ◽  
W. Belzig
Keyword(s):  
Topological Structure ◽  
Gauge Theories ◽  
Topological States Of Matter ◽  
Three Dimensions ◽  
Gauge Fields ◽  
Quantum Geometry ◽  
Central Concept ◽  
Dirac Monopole ◽  
Topological States ◽  
Phase Differences

Topology in general but also topological objects such as monopoles are a central concept in physics. They are prime examples for the intriguing physics of gauge theories and topological states of matter. Vector monopoles are already frequently discussed such as the well-established Dirac monopole in three dimensions. Less known are tensor monopoles giving rise to tensor gauge fields. Here we report that tensor monopoles can potentially be realized in superconducting multi-terminal systems using the phase differences between superconductors as synthetic dimensions. In a first proposal we suggest a circuit of superconducting islands featuring charge states to realize a tensor monopole. As a second example we propose a triple dot system coupled to multiple superconductors that also gives rise to such a topological structure. All proposals can be implemented with current experimental means and the monopole readily be detected by measuring the quantum geometry.

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