scholarly journals Pressure-induced superconductivity and modification of Fermi surface in type-II Weyl semimetal NbIrTe4

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Qing-Ge Mu ◽  
Feng-Ren Fan ◽  
Horst Borrmann ◽  
Walter Schnelle ◽  
Yan Sun ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Electrical Transport ◽  
Chemical Potential ◽  
Theoretical Calculations ◽  
Quantum Oscillation ◽  
Type Ii ◽  
Superconducting Transition ◽  
Weyl Semimetal ◽  
Spectroscopy Studies ◽  
Structure Calculations

AbstractWeyl semimetals (WSMs) hosting Weyl points (WPs) with different chiralities attract great interest as an object to study chirality-related physical properties, topological phase transitions, and topological superconductivity. Quantum oscillation measurements and theoretical calculations imply that the type-II WPs in NbIrTe4 are robust against the shift of chemical potential making it a good material for pressure studies on topological properties. Here we report the results of electrical transport property measurements and Raman spectroscopy studies under pressures up to 65.5 GPa accompanied by theoretical electronic structure calculations. Hall resistivity data reveal an electronic transition indicated by a change of the charge carrier from multiband character to hole-type at ~12 GPa, in agreement with the calculated Fermi surface. An onset of superconducting transition is observed at pressures above 39 GPa, with critical temperature increasing as pressure increases. Moreover, theoretical calculations indicate that WPs persist up to highly reduced unit cell volume (−17%), manifesting that NbIrTe4 is a candidate of topological superconductor.

Quantum oscillation measurements of a type-II Weyl semimetal

Scilight ◽  
2020 ◽  
Vol 2020 (49) ◽  
pp. 491103
Author(s):  
Meeri Kim
Keyword(s):  
Quantum Oscillation ◽  
Type Ii ◽  
Weyl Semimetal

Transport signatures of temperature-induced chemical potential shift and Lifshitz transition in layered type-II Weyl semimetal TaIrTe4

2D Materials ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 015020
Author(s):  
Yu Jian ◽  
Quansheng Wu ◽  
Meng Yang ◽  
Qi Feng ◽  
Junxi Duan ◽  
...  
Keyword(s):  
Chemical Potential ◽  
Type Ii ◽  
Potential Shift ◽  
Weyl Semimetal ◽  
Lifshitz Transition

The Meissner effect in high-temperature hydrogen-rich superconductors under high pressure

2021 ◽  
Author(s):  
Vasily Minkov ◽  
Sergey Bud'ko ◽  
Fedor Balakirev ◽  
Vitali Prakapenka ◽  
Stella Chariton ◽  
...  
Keyword(s):  
Electrical Transport ◽  
Room Temperature ◽  
Meissner Effect ◽  
Type Ii ◽  
Superconducting Transition ◽  
London Penetration Depth ◽  
Ginzburg Landau ◽  
Type Ii Superconductors ◽  
Definitive Evidence ◽  
Superconducting Parameters

Abstract In the last few years, the superconducting transition temperature, Tc, of hydrogen-rich compounds has increased dramatically, and is now approaching room temperature. However, the pressures at which these materials are stable exceed one million atmospheres and limit the number of available experimental probes - superconductivity has been primarily identified based on electrical transport measurements. Here, we report definitive evidence of the Meissner effect – a key feature of superconductivity – in H3S and LaH10. Furthermore, we have determined characteristic superconducting parameters: a lower critical field Hc1 of ∼1.9 and ∼1.0 T, and a London penetration depth λL of ∼13 and ∼21 nm in Im-3m-H3S and Fm-3m-LaH10, respectively. These compounds have low values of the Ginzburg-Landau parameter κ ∼7–14 and belong to the group of “moderate” type II superconductors.

scholarly journals Tuning the electrical transport of type II Weyl semimetal WTe2 nanodevices by Ga+ ion implantation

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Dongzhi Fu ◽  
Bingwen Zhang ◽  
Xingchen Pan ◽  
Fucong Fei ◽  
Yongda Chen ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Electrical Transport ◽  
Type Ii ◽  
Weyl Semimetal

Tuning the electrical transport of type II Weyl semimetal WTe2 nanodevices by Mo doping

2018 ◽  
Vol 29 (13) ◽  
pp. 135705 ◽  
Author(s):  
Dongzhi Fu ◽  
Xingchen Pan ◽  
Zhanbin Bai ◽  
Fucong Fei ◽  
Gilberto A Umana-Membreno ◽  
...  
Keyword(s):  
Electrical Transport ◽  
Type Ii ◽  
Mo Doping ◽  
Weyl Semimetal

scholarly journals Photonic spin Hall effect on the surfaces of type-I and type-II Weyl semimetals

Nanophotonics ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 715-723 ◽  
Author(s):  
Guang Yi Jia ◽  
Zhen Xian Huang ◽  
Qiao Yun Ma ◽  
Geng Li
Keyword(s):  
Hall Effect ◽  
Chemical Potential ◽  
Research Area ◽  
Spin Hall Effect ◽  
Transverse Spin ◽  
Type I ◽  
Type Ii ◽  
Incident Wavelength ◽  
Weyl Semimetal ◽  
Variation Trends

AbstractTopological optics is an emerging research area in which various topological and geometrical ideas are being proposed to design and manipulate the behaviors of photons. Here, the photonic spin Hall effect on the surfaces of topological Weyl semimetal (WSM) films was studied. Our results show that the spin-dependent splitting (i.e. photonic spin Hall shifts) induced by the spin-orbit interaction is little sensitive to the tilt αt of Weyl nodes and the chemical potential μ in type-I WSM film. In contrast, photonic spin Hall shifts in both the in-plane and transverse directions present versatile dependent behaviors on the αt and μ in type-II WSM film. In particular, the largest in-plane and transverse spin Hall shifts appear at the tilts between −2 and −3, which are ~40 and ~10 times of the incident wavelength, respectively. Nevertheless, the largest spin Hall shifts for type-II WSM film with positive αt are only several times of incident wavelength. Moreover, the photonic spin Hall shifts also exhibit different variation trends with decreasing the chemical potential for different signs of αt in type-II WSM films. This dependence of photonic spin Hall shifts on tilt orientation in type-II WSM films has been explained by time-reversal-symmetry-breaking Hall conductivities in WSMs.

scholarly journals Quantum transport evidence of Weyl fermions in an epitaxial ferromagnetic oxide

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Kosuke Takiguchi ◽  
Yuki K. Wakabayashi ◽  
Hiroshi Irie ◽  
Yoshiharu Krockenberger ◽  
Takuma Otsuka ◽  
...  
Keyword(s):  
Quantum Transport ◽  
Molecular Beam ◽  
Transport Phenomena ◽  
Chiral Anomaly ◽  
Quantum Oscillation ◽  
Weyl Semimetal ◽  
Clear Guideline ◽  
Structure Calculations ◽  
Cyclotron Mass ◽  
Weyl Fermions

Abstract Magnetic Weyl semimetals have novel transport phenomena related to pairs of Weyl nodes in the band structure. Although the existence of Weyl fermions is expected in various oxides, the evidence of Weyl fermions in oxide materials remains elusive. Here we show direct quantum transport evidence of Weyl fermions in an epitaxial 4d ferromagnetic oxide SrRuO3. We employ machine-learning-assisted molecular beam epitaxy to synthesize SrRuO3 films whose quality is sufficiently high to probe their intrinsic transport properties. Experimental observation of the five transport signatures of Weyl fermions—the linear positive magnetoresistance, chiral-anomaly-induced negative magnetoresistance, π phase shift in a quantum oscillation, light cyclotron mass, and high quantum mobility of about 10,000 cm2V−1s−1—combined with first-principles electronic structure calculations establishes SrRuO3 as a magnetic Weyl semimetal. We also clarify the disorder dependence of the transport of the Weyl fermions, which gives a clear guideline for accessing the topologically nontrivial transport phenomena.

scholarly journals Fermi surface of the skutterudite CoSb3 : Quantum oscillations and band-structure calculations

2021 ◽  
Vol 103 (8) ◽  
Author(s):  
M. Naumann ◽  
P. Mokhtari ◽  
Z. Medvecka ◽  
F. Arnold ◽  
M. Pillaca ◽  
...  
Keyword(s):  
Band Structure ◽  
Fermi Surface ◽  
Quantum Oscillations ◽  
Band Structure Calculations ◽  
Structure Calculations

scholarly journals Aspects of quantum information in finite density field theory

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Lucas Daguerre ◽  
Raimel Medina ◽  
Mario Solís ◽  
Gonzalo Torroba
Keyword(s):  
Field Theory ◽  
Quantum Information ◽  
Mutual Information ◽  
Fermi Surface ◽  
Relative Entropy ◽  
Chemical Potential ◽  
Operator Product ◽  
Dirac Fermions ◽  
Long Distance ◽  
Finite Density

Abstract We study different aspects of quantum field theory at finite density using methods from quantum information theory. For simplicity we focus on massive Dirac fermions with nonzero chemical potential, and work in 1 + 1 space-time dimensions. Using the entanglement entropy on an interval, we construct an entropic c-function that is finite. Unlike what happens in Lorentz-invariant theories, this c-function exhibits a strong violation of monotonicity; it also encodes the creation of long-range entanglement from the Fermi surface. Motivated by previous works on lattice models, we next calculate numerically the Renyi entropies and find Friedel-type oscillations; these are understood in terms of a defect operator product expansion. Furthermore, we consider the mutual information as a measure of correlation functions between different regions. Using a long-distance expansion previously developed by Cardy, we argue that the mutual information detects Fermi surface correlations already at leading order in the expansion. We also analyze the relative entropy and its Renyi generalizations in order to distinguish states with different charge and/or mass. In particular, we show that states in different superselection sectors give rise to a super-extensive behavior in the relative entropy. Finally, we discuss possible extensions to interacting theories, and argue for the relevance of some of these measures for probing non-Fermi liquids.

scholarly journals Ultrafast dynamical Lifshitz transition

2021 ◽  
Vol 7 (17) ◽  
pp. eabd9275
Author(s):  
Samuel Beaulieu ◽  
Shuo Dong ◽  
Nicolas Tancogne-Dejean ◽  
Maciej Dendzik ◽  
Tommaso Pincelli ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Colossal Magnetoresistance ◽  
Surface Topology ◽  
Strongly Correlated ◽  
Many Body ◽  
Time Resolved ◽  
Weyl Semimetal ◽  
Lifshitz Transition ◽  
Fermi Surface Topology ◽  
Many Body Systems

Fermi surface is at the heart of our understanding of metals and strongly correlated many-body systems. An abrupt change in the Fermi surface topology, also called Lifshitz transition, can lead to the emergence of fascinating phenomena like colossal magnetoresistance and superconductivity. While Lifshitz transitions have been demonstrated for a broad range of materials by equilibrium tuning of macroscopic parameters such as strain, doping, pressure, and temperature, a nonequilibrium dynamical route toward ultrafast modification of the Fermi surface topology has not been experimentally demonstrated. Combining time-resolved multidimensional photoemission spectroscopy with state-of-the-art TDDFT+U simulations, we introduce a scheme for driving an ultrafast Lifshitz transition in the correlated type-II Weyl semimetal Td-MoTe2. We demonstrate that this nonequilibrium topological electronic transition finds its microscopic origin in the dynamical modification of the effective electronic correlations. These results shed light on a previously unexplored ultrafast scheme for controlling the Fermi surface topology in correlated quantum materials.

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