Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where C. Meingast is active.

Publication


Featured researches published by C. Meingast.


Physical Review B | 2015

Emergence of the nematic electronic state in FeSe

Watson; T. K. Kim; Amir A. Haghighirad; Nr Davies; Alix McCollam; A. Narayanan; S.F. Blake; Yulin Chen; S. Ghannadzadeh; Aj Schofield; M. Hoesch; C. Meingast; Th. Wolf; Amalia I. Coldea

We present a comprehensive study of the evolution of the nematic electronic structure of FeSe using high-resolution angle-resolved photoemission spectroscopy (ARPES), quantum oscillations in the normal state, and elastoresistance measurements. Our high-resolution ARPES allows us to track the Fermi surface deformation from fourfold to twofold symmetry across the structural transition at ∼87K, which is stabilized as a result of the dramatic splitting of bands associated with dxz and dyz character in the presence of strong electronic interactions. The low-temperature Fermi surface is that of a compensated metal consisting of one hole and two electron bands and is fully determined by combining the knowledge from ARPES and quantum oscillations. A manifestation of the nematic state is the significant increase in the nematic susceptibility approaching the structural transition that we detect from our elastoresistance measurements on FeSe. The dramatic changes in electronic structure cannot be explained by the small lattice distortion and, in the absence of magnetic fluctuations above the structural transition, point clearly towards an electronically driven transition in FeSe, stabilized by orbital-charge ordering.


Physical Review B | 2013

Lack of coupling between superconductivity and orthorhombic distortion in stoichiometric single-crystalline FeSe

A. E. Böhmer; F. Hardy; F. Eilers; D. Ernst; P. Adelmann; P. Schweiss; Th. Wolf; C. Meingast

The coupling between superconductivity and orthorhombic distortion is studied in vapor-grown FeSe single crystals using high-resolution thermal-expansion measurements. In contrast to the Ba122-based (Ba122) superconductors, we find that superconductivity does not reduce the orthorhombicity below


Physical Review B | 2014

Anomalous Fermi surface in FeSe seen by Shubnikov–de Haas oscillation measurements

Taichi Terashima; Naoki Kikugawa; Andhika Kiswandhi; Eun Sang Choi; J. S. Brooks; S. Kasahara; Tatsuya Watashige; Hiroaki Ikeda; T. Shibauchi; Y. Matsuda; Thomas Wolf; A. E. Böhmer; F. Hardy; C. Meingast; H. v. Löhneysen; Michi-To Suzuki; Ryotaro Arita; Shinya Uji

{T}_{c}


Physical Review Letters | 2014

Nematic susceptibility of hole-doped and electron-doped BaFe2As2 iron-based superconductors from shear modulus measurements.

A. E. Böhmer; Philipp Burger; F. Hardy; Th. Wolf; P. Schweiss; Rainer Fromknecht; Marius Reinecker; W. Schranz; C. Meingast

. Instead we find that superconductivity couples strongly to the in-plane area, which explains the large hydrostatic pressure effects. We discuss our results in light of the spin-nematic scenario and argue that FeSe has many features that are quite different from typical Fe-based superconductors.


Physical Review Letters | 2013

Evidence of Strong Correlations and Coherence-Incoherence Crossover in the Iron Pnictide Superconductor KFe2As2

F. Hardy; A. E. Böhmer; Dai Aoki; Philipp Burger; Th. Wolf; P. Schweiss; Rolf Heid; P. Adelmann; Y. X. Yao; G. Kotliar; Jörg Schmalian; C. Meingast

We have observed Shubnikov-de Haas oscillations in FeSe. The Fermi surface deviates significantly from predictions of band-structure calculations and most likely consists of one electron and one hole thin cylinder. The carrier density is in the order of 0.01 carriers/ Fe, an order-of-magnitude smaller than predicted. Effective Fermi energies as small as 3.6 meV are estimated. These findings call for elaborate theoretical investigations incorporating both electronic correlations and orbital ordering.


Physica C-superconductivity and Its Applications | 1993

Uniaxial pressure dependence of Tc of untwinned YBa2Cu3Ox single crystals for x=6.5–7

O. Kraut; C. Meingast; G. Bräuchle; Helmut Claus; A. Erb; G. Müller-Vogt; H. Wühl

The nematic susceptibility, χφ, of hole-doped Ba(1-x)K(x)Fe2As2 and electron-doped Ba(Fe(1-x)Co(x))2As2 iron-based superconductors is obtained from measurements of the elastic shear modulus using a three-point bending setup in a capacitance dilatometer. Nematic fluctuations, although weakened by doping, extend over the whole superconducting dome in both systems, suggesting their close tie to superconductivity. Evidence for quantum critical behavior of χφ is, surprisingly, only found for Ba(Fe(1-x)Co(x))2As2 and not for Ba(1-x)K(x)Fe2As2--the system with the higher maximal Tc value.


Physical Review Letters | 2001

Phase Fluctuations and the Pseudogap in YBa2Cu3Ox

C. Meingast; Volker Pasler; P. Nagel; A. I. Rykov; S. Tajima; Peter Olsson

Using resistivity, heat-capacity, thermal-expansion, and susceptibility measurements we study the normal-state behavior of KFe2As2. Both the Sommerfeld coefficient (γ≈103 mJ mol(-1) K(-2)) and the Pauli susceptibility (χ≈4×10(-4)) are strongly enhanced, which confirm the existence of heavy quasiparticles inferred from previous de Haas-van Alphen and angle-resolved photoemission spectroscopy experiments. We discuss this large enhancement using a Gutzwiller slave-boson mean-field calculation, which shows the proximity of KFe2As2 to an orbital-selective Mott transition. The temperature dependence of the magnetic susceptibility and the thermal expansion provide strong experimental evidence for the existence of a coherence-incoherence crossover, similar to what is found in heavy fermion and ruthenate compounds, due to Hunds coupling between orbitals.


Physical Review B | 2010

Calorimetric evidence of multiband superconductivity in Ba ( Fe 0.925 Co 0.075 ) 2 As 2 single crystals

F. Hardy; Th. Wolf; R. A. Fisher; Robert Eder; P. Schweiss; P. Adelmann; H. v. Löhneysen; C. Meingast

Abstract The dependence of Tc on uniaxial pressure dTc/dpi(i= a, b, c) is determined for untwinned YBa2Cu3Ox single crystals as a function of O-content using ultrahigh-resolution thermal-expansion data and the Ehrenfest relationship. The dTc/dpi values are found to be highly anisotropic and are likely due to several different effects. For uniaxial-pressure applied parallel to the c-axis, we find a strong O-content (or carrier density) dependence of the dTc/dpb values, which have opposite signs charge transfer model. This model does not, however, explain the large dTc/dpa and dTc/dpb values, which have opposite signs and do not show a strong O-content dependence except at x=6.7, where both dTc/dpa and dTc/dpb values increase sharply. The a, b effects are discussed in terms of the orthorhombic distortion.


Physical Review Letters | 1998

3D-XY CRITICAL FLUCTUATIONS OF THE THERMAL EXPANSIVITY IN DETWINNED YBA2CU3O7-DELTA SINGLE CRYSTALS NEAR OPTIMAL DOPING

Volker Pasler; P. Schweiss; C. Meingast; Bernhard Obst; H. Wühl; Alexandre I. Rykov; S. Tajima

: The thermodynamics of the superconducting transition is studied as a function of doping using high-resolution expansivity data of YBa(2)Cu(3)O (x) single crystals and Monte Carlo simulations of the anisotropic 3D- XY model. We directly show that T(c) of underdoped YBa(2)Cu(3)O (x) is strongly suppressed from its mean-field value (T(MF)(c)) by phase fluctuations of the superconducting order parameter. For overdoped YBa(2)Cu(3)O (x) fluctuation effects are greatly reduced and T(c) approximately T(MF)(c). We find that T(MF)(c) exhibits a similar doping dependence as the pseudogap energy, naturally suggesting that the pseudogap arises from phase-incoherent Cooper pairing.


Physical Review Letters | 2013

Scaling between magnetic and lattice fluctuations in iron pnictide superconductors

Rafael M. Fernandes; A. E. Böhmer; C. Meingast; Jörg Schmalian

We report on the determination of the electronic heat capacity of a slightly overdoped (x = 0.075) Ba(Fe1-xCox)2As2 single crystal with a Tc of 21.4 K. Our analysis of the temperature dependence of the superconducting-state specific heat provides strong evidence for a two-band s-wave order parameter with gap amplitudes 2D1(0)/kBTc=1.9 and 2D2(0)/kBTc=4.4. Our result is consistent with the recently predicted s+- order parameter [I. I. Mazin et al., Phys. Rev. Lett. 101, 057003 (2008)].

Collaboration


Dive into the C. Meingast's collaboration.

Top Co-Authors

Avatar

F. Hardy

Karlsruhe Institute of Technology

View shared research outputs
Top Co-Authors

Avatar

Th. Wolf

Karlsruhe Institute of Technology

View shared research outputs
Top Co-Authors

Avatar

Thomas Wolf

Karlsruhe Institute of Technology

View shared research outputs
Top Co-Authors

Avatar

H. v. Löhneysen

Karlsruhe Institute of Technology

View shared research outputs
Top Co-Authors

Avatar

P. Adelmann

Karlsruhe Institute of Technology

View shared research outputs
Top Co-Authors

Avatar

A. E. Böhmer

Karlsruhe Institute of Technology

View shared research outputs
Top Co-Authors

Avatar

P. Schweiss

Karlsruhe Institute of Technology

View shared research outputs
Top Co-Authors

Avatar

Liran Wang

Karlsruhe Institute of Technology

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

K. Grube

Karlsruhe Institute of Technology

View shared research outputs
Researchain Logo
Decentralizing Knowledge