Fluctuations and the Higgs Mechanism in Underdoped Cuprates

The physics of the pseudogap phase of high-temperature cuprate superconductors has been an enduring mystery over the past 30 years. The ubiquitous presence of the pseudogap phase in underdoped cuprates suggests that understanding it is key to unraveling the origin of high-temperature superconductivity. We review various theoretical approaches to this problem, emphasizing the concept of emergent symmetries in the underdoped region of those compounds. We differentiate these theories by considering a few fundamental questions related to the rich phenomenology of these materials. Lastly, we discuss a recent idea regarding two kinds of entangled preformed pairs that open a gap at the pseudogap onset temperature, T*, through a specific Higgs mechanism. We review the experimental consequences of this line of thought.

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What is strange about high-temperature superconductivity in cuprates?

International Journal of Modern Physics B ◽

10.1142/s0217979217450059 ◽

2017 ◽

Vol 31 (25) ◽

pp. 1745005

Author(s):

I. Božović ◽

X. He ◽

J. Wu ◽

A. T. Bollinger

Keyword(s):

Phase Diagram ◽

Cuprate Superconductors ◽

High Temperature Superconductivity ◽

Einstein Condensation ◽

Strongly Correlated ◽

Bose Einstein Condensation ◽

Ultimate Question ◽

Underdoped Cuprates ◽

Bose Einstein ◽

Superconducting Parameters

Cuprate superconductors exhibit many features, but the ultimate question is why the critical temperature ([Formula: see text]) is so high. The fundamental dichotomy is between the weak-pairing, Bardeen–Cooper–Schrieffer (BCS) scenario, and Bose–Einstein condensation (BEC) of strongly-bound pairs. While for underdoped cuprates it is hotly debated which of these pictures is appropriate, it is commonly believed that on the overdoped side strongly-correlated fermion physics evolves smoothly into the conventional BCS behavior. Here, we test this dogma by studying the dependence of key superconducting parameters on doping, temperature, and external fields, in thousands of cuprate samples. The findings do not conform to BCS predictions anywhere in the phase diagram.

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Unusual symmetries of the order parameter in cuprates

Science & Technology Development Journal - Engineering and Technology ◽

10.32508/stdjet.v2i4.674 ◽

2020 ◽

Vol 2 (4) ◽

pp. 207-212

Author(s):

Tran Van Luong ◽

Nguyen Thi Ngoc Nu

Keyword(s):

High Temperature ◽

Order Parameter ◽

Cuprate Superconductors ◽

High Temperature Superconductivity ◽

Spin Fluctuation ◽

High Temperature Superconductors ◽

Coulomb Repulsion ◽

Bcs Theory ◽

S Wave ◽

Wave Symmetry

The BCS superconducting theory, introduced by J. Bardeen, L. Cooper and R. Schriffer in 1957, succeeded in describing and satis-factorily explaining the nature of superconductivity for low-temperature superconductors. However, the BCS theory cannot explain the properties of high-temperature superconductors, discovered by J. G. Bednorz and K. A. Müller in 1986. Although scientists have found a lot of new superconductors and their transition temperatures are constantly increasing, most high-temperature superconductors are found by experiment and so far no theory can fully explain their properties. Many previous studies have suggested that the order parameter in high-temperature copper-based superconductors (cuprate superconductors - cuprates) is in the form of d-wave symmetry, but recent results show that the order parameter has an extended s-wave symmetry (extended s wave). Studying the symmetric forms of order parameters in cuprate can contribute to understanding the nature of high-temperature superconductivity. In this article, the authors present an overview of the development of high-temperature supercon-ductors over the past 30 years and explains unusual symmetries of the order parameter in copper-based superconductors. The com-petition of three coupling mechanisms of electrons in cuprates (the mechanism of coupling through coulomb repulsion, electron-phonon mechanism and spin-fluctuation mechanism) affects the unusual symmetry of the order parameter. The solution of the self-consistency equation in simple cases has been found and the ability to move the phase within the superconducting state has been shown.

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RAMAN SCATTERING IN IRON-BASED SUPERCONDUCTORS

Modern Physics Letters B ◽

10.1142/s0217984912300207 ◽

2012 ◽

Vol 26 (28) ◽

pp. 1230020 ◽

Cited By ~ 8

Author(s):

A. M. ZHANG ◽

Q. M. ZHANG

Keyword(s):

High Temperature ◽

Raman Scattering ◽

Cuprate Superconductors ◽

High Temperature Superconductivity ◽

Industrial Applications ◽

Layered Compounds ◽

Correlated Electron Systems ◽

Correlated Electron ◽

History Of ◽

Iron Based

Iron-based superconducting layered compounds have the second highest transition temperature after cuprate superconductors. Their discovery is a milestone in the history of high-temperature superconductivity and will have profound implications for high-temperature superconducting mechanism as well as industrial applications. Raman scattering has been extensively applied to correlated electron systems including the new superconductors due to its unique ability to probe multiple primary excitations and their coupling. In this review, we will give a brief summary of the existing Raman experiments in the iron-based materials and their implications for pairing mechanism in particular. And we will also address some open issues from the experiments.

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Theory of high-temperature superconductivity in underdoped cuprates; the unusual electronic structure and the origin of the pseudogap

Journal of Physics Condensed Matter ◽

10.1088/0953-8984/10/49/023 ◽

1998 ◽

Vol 10 (49) ◽

pp. 11345-11364 ◽

Cited By ~ 4

Author(s):

Hiroshi Kamimura ◽

Kazushi Nomura ◽

Akihiro Sano

Keyword(s):

Electronic Structure ◽

High Temperature ◽

High Temperature Superconductivity ◽

Underdoped Cuprates

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Pressure induced superconductivity in MnSe

Nature Communications ◽

10.1038/s41467-021-25721-1 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

T. L. Hung ◽

C. H. Huang ◽

L. Z. Deng ◽

M. N. Ou ◽

Y. Y. Chen ◽

...

Keyword(s):

High Pressure ◽

High Temperature ◽

Structural Change ◽

High Temperature Superconductivity ◽

The Rich ◽

Related Compounds ◽

Insight Into

AbstractThe rich phenomena in the FeSe and related compounds have attracted great interests as it provides fertile material to gain further insight into the mechanism of high temperature superconductivity. A natural follow-up work was to look into the possibility of superconductivity in MnSe. We demonstrated in this work that high pressure can effectively suppress the complex magnetic characters of MnSe, and induce superconductivity with Tc ~ 5 K at pressure ~12 GPa confirmed by both magnetic and resistive measurements. The highest Tc is ~ 9 K (magnetic result) at ~35 GPa. Our observations suggest the observed superconductivity may closely relate to the pressure-induced structural change. However, the interface between the metallic and insulating boundaries may also play an important role to the pressure induced superconductivity in MnSe.

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The Mysteries of Charge Order and Charge Fluctuations in Cuprate Superconductors

10.7566/jpsht.1.062 ◽

2021 ◽

Vol 1 ◽

Keyword(s):

High Temperature ◽

Cuprate Superconductors ◽

High Temperature Superconductivity ◽

Charge Order ◽

Charge Fluctuations

This Special Topics issue condenses the latest research on the enigmatic characteristics of high-temperature superconductivity in cuprates through the observation and elucidation of charge order, charge fluctuations, and other phenomena.

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Exploring the Pseudogap in Cuprate Superconductors

10.7566/jpsht.1.020 ◽

2021 ◽

Vol 1 ◽

Keyword(s):

High Temperature ◽

Cuprate Superconductors ◽

High Temperature Superconductivity ◽

Degree Of Freedom ◽

Crystal Symmetry ◽

Oxide Materials ◽

Potential Link

Electronic nematic correlation, in which electronic degree of freedom breaks the crystal symmetry, was found to have a potential link to the origin of high-temperature superconductivity in cooper oxide materials.

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Itinerant Vibrons and High-Temperature Superconductivity*

MRS Proceedings ◽

10.1557/proc-658-gg2.2 ◽

2000 ◽

Vol 658 ◽

Author(s):

John B. Goodenough

Keyword(s):

High Temperature ◽

Room Temperature ◽

High Temperature Superconductivity ◽

Phase Segregation ◽

Optical Mode ◽

Temperature Changes ◽

Critical Composition ◽

Underdoped Region ◽

Small Polarons ◽

Electronic Behavior

ABSTRACTThe La2−xSrxCuO4 phase diagram is interpreted within the framework of a transition from localized to itinerant electronic behavior. In the underdoped region 0 < x < 0.1, holes in the x2 – y2 band are not small polarons; each occupies a mobile correlation bag of 5 to 6 copper centers at temperatures T > TF, a spinodal phase segregation into the parent antiferromagnetic phase and a polaron liquid is accomplished below TF by cooperative oxygen displacements. In the overdoped compositions > x > 0.25, holes are excluded from strong-correlation fluctuations within a Fermi liquid. In the intermediate range 0.1 < x < 0.25, the polaron liquid formed below room temperature changes character with increasing x and decreasing T. In the polaron liquid, mobile two-hole bags of four copper centers order with decreasing temperature into alternate CuO-Cu rows of a superconductive CuO2 sheet at a critical composition xc ≍ 1/6. It is argued that hybridization of itinerant electrons with optical-mode phonons propagating along the Cu-O-Cu rows produces heavy electrons responsible for high-temperature superconductivity.

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INTERPLAY OF D-WAVE SUPERCONDUCTIVITY AND ANTIFERROMAGNETISM IN THE CUPRATE SUPERCONDUCTORS: PHASE SEPARATION AND THE PSEUDOGAP PHASE DIAGRAM

Modern Physics Letters B ◽

10.1142/s0217984905009262 ◽

2005 ◽

Vol 19 (25) ◽

pp. 1295-1302 ◽

Cited By ~ 5

Author(s):

W. P. SU

Keyword(s):

Phase Diagram ◽

Phase Separation ◽

Cuprate Superconductors ◽

Nearest Neighbor ◽

Superconducting Transition ◽

Zero Temperature ◽

Pseudogap Phase ◽

Underdoped Cuprates ◽

D Wave ◽

Interaction Free Energy

To understand the interplay of d-wave superconductivity and antiferromagnetism in the cuprates, we consider a two-dimensional extended Hubbard model with nearest neighbor attractive interaction. Free energy of the homogeneous (coexisting superconducting and antiferromagnetic) state calculated as a function of the band filling shows a region of phase separation. The phase separation caused by the intersite attractive force leads to novel insights into salient features of the pseudogap phase diagram. In particular, the upper crossover curve can be identified with the phase separation boundary. At zero temperature, the boundary constitutes a critical point. The inhomogeneity observed in the underdoped cuprates is a consequence of incomplete phase separation. The disorder (inhomogeneity) brings about the disparity between the high pseudogap temperature and the low bulk superconducting transition temperature.

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