Smeared nematic quantum phase transitions due to rare-region effects in inhomogeneous systems

Cui, Tianbai; Fernandes, Rafael M.

doi:10.1103/physrevb.98.085117

Cited by 8 publications

(5 citation statements)

References 45 publications

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“…Quenched disorder can lead to rare-region effects which fundamentally change the properties of the system upon approach to the critical point, for instance, z develops a temperature dependence. This has recently been proposed as one possible explanation for the non-power-law behavior seen in similar elastoresistivity measurements 25 . Rare-region effects and qualitatively similar deviations from power-law scaling have also recently been observed in the related material, FeSe 1− x S x 26 .…”

Section: Discussionmentioning

confidence: 68%

Comparison of temperature and doping dependence of elastoresistivity near a putative nematic quantum critical point

et al. 2022

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Strong electronic nematic fluctuations have been discovered near optimal doping for several families of Fe-based superconductors, motivating the search for a possible link between these fluctuations, nematic quantum criticality, and high temperature superconductivity. Here we probe a key prediction of quantum criticality, namely power-law dependence of the associated nematic susceptibility as a function of composition and temperature approaching the compositionally tuned putative quantum critical point. To probe the ‘bare’ quantum critical point requires suppression of the superconducting state, which we achieve by using large magnetic fields, up to 45 T, while performing elastoresistivity measurements to follow the nematic susceptibility. We performed these measurements for the prototypical electron-doped pnictide, Ba(Fe1−xCox)2As2, over a dense comb of dopings. We find that close to the putative quantum critical point, the elastoresistivity appears to obey power-law behavior as a function of composition over almost a decade of variation in composition. Paradoxically, however, we also find that the temperature dependence for compositions close to the critical value cannot be described by a single power law.

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Section: Discussionmentioning

confidence: 68%

Comparison of temperature and doping dependence of elastoresistivity near a putative nematic quantum critical point

et al. 2022

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“…Quenched disorder is perfectly correlated in time, but can harbor a spatially varying order parameter. In this situation, a smeared phase transition can occur, where ordered islands form within a disordered bulk [5,6]. Moreover, when order parameter fluctuations within the islands are non-negligible, a Griffiths phase can emerge which leads to continuously varying critical exponents as a function of temperature and control parameter, fundamentally different to clean systems [7][8][9][10][11][12][13].…”

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confidence: 99%

Signatures of a Quantum Griffiths Phase Close to an Electronic Nematic Quantum Phase Transition

et al. 2021

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In the vicinity of a quantum critical point, quenched disorder can lead to a quantum Griffiths phase, accompanied by an exotic power-law scaling with a continuously varying dynamical exponent that diverges in the zero-temperature limit. Here, we investigate a nematic quantum critical point in the iron-based superconductor FeSe0.89S0.11 using applied hydrostatic pressure. We report an unusual crossing of the magnetoresistivity isotherms in the non-superconducting normal state which features a continuously varying dynamical exponent over a large temperature range. We interpret our results in terms of a quantum Griffiths phase caused by nematic islands that result from the local distribution of Se and S atoms. At low temperatures, the Griffiths phase is masked by the emergence of a Fermi liquid phase due to a strong nematoelastic coupling and a Lifshitz transition that changes the topology of the Fermi surface.

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“…More investigations, like the Synchrotron diffraction, Raman scattering, or INS will be needed to further understand the origin of the Griffiths phase. Furthermore, it is predicted that the Griffiths effect can smear the nematic quantum phase transition in inhomogeneous system [69] and Sr(Fe1-xMnx)2As2 system could be a candidate to fulfill that. Compared with other transition metal doped AFe2As2 (A = Eu, Sr, Ba, and Ca) systems [25][26][27]55,57,[70][71][72][73], the behavior caused by Griffiths effect has only been found in Mn-doped systems [45], to the best of our knowledge.…”

Section: Resultsmentioning

confidence: 99%

Miscibility gap and possible intrinsic Griffiths phase in Sr(Fe1−xMnx)2As2 crystals grown

et al. 2021

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The crystal structure, magnetic, electronic, and thermal properties of Mndoped SrFe2As2 crystals have been systematically investigated. A miscibility gap is found in the system from x = 0.4362(4) to x = 0.9612(9). For x < 0.2055(2), the single crystals holding tetragonal structure (space group I4/mmm (no. 139)) have a continuously enlarged lattice parameter c, followed by a phase separation with crystals holding both tetragonal and trigonal structures up to x = 0.4362(4). Beyond the miscibility gap, the crystals with x > 0.9612(9) hold the trigonal structure (space group P-3m1 (no. 164)). Moreover, the spin density wave ordering for x = 0 to x = 0.0973(1) is suppressed, followed by an abnormal and broadened increase of the ordering temperature for x = 0.0973(1) to x = 0.2055(2). Eliminating the possibility of real-space phase separation of Mn and Fe based on the results of X-ray diffraction, this novel phenomenon can be attributed to a possible intrinsic Griffiths phase. No any superconducting signals are observed down to 2 K in the whole composition range with 0 < x < 1. A phase diagram with multi-critical points of Mn-doped SrFe2As2 system is established accordingly.

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Smeared nematic quantum phase transitions due to rare-region effects in inhomogeneous systems

Cited by 8 publications

References 45 publications

Comparison of temperature and doping dependence of elastoresistivity near a putative nematic quantum critical point

Comparison of temperature and doping dependence of elastoresistivity near a putative nematic quantum critical point

Signatures of a Quantum Griffiths Phase Close to an Electronic Nematic Quantum Phase Transition

Miscibility gap and possible intrinsic Griffiths phase in Sr(Fe1−xMnx)2As2 crystals grown

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