scholarly journals Pressure-induced high-temperature superconductivity retained without pressure in FeSe single crystals

2021 ◽  
Vol 118 (28) ◽  
pp. e2108938118
Author(s):  
Liangzi Deng ◽  
Trevor Bontke ◽  
Rabin Dahal ◽  
Yu Xie ◽  
Bin Gao ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperature Superconductivity ◽  
Ambient Pressure ◽  
Superconducting Transition ◽  
Elastic Band ◽  
New Era ◽  
Ab Initio Simulations ◽  
Sustained Effort ◽  
Minimal Effort ◽  
Room Temperature Superconductivity

To raise the superconducting-transition temperature (Tc) has been the driving force for the long-sustained effort in superconductivity research. Recent progress in hydrides with Tcs up to 287 K under pressure of 267 GPa has heralded a new era of room temperature superconductivity (RTS) with immense technological promise. Indeed, RTS will lift the temperature barrier for the ubiquitous application of superconductivity. Unfortunately, formidable pressure is required to attain such high Tcs. The most effective relief to this impasse is to remove the pressure needed while retaining the pressure-induced Tc without pressure. Here, we show such a possibility in the pure and doped high-temperature superconductor (HTS) FeSe by retaining, at ambient pressure via pressure quenching (PQ), its Tc up to 37 K (quadrupling that of a pristine FeSe at ambient) and other pressure-induced phases. We have also observed that some phases remain stable without pressure at up to 300 K and for at least 7 d. The observations are in qualitative agreement with our ab initio simulations using the solid-state nudged elastic band (SSNEB) method. We strongly believe that the PQ technique developed here can be adapted to the RTS hydrides and other materials of value with minimal effort.

Crystal Growth of High Temperature Superconductors

MRS Bulletin ◽  
1988 ◽  
Vol 13 (10) ◽  
pp. 56-61 ◽  
Author(s):  
H.J. Scheel ◽  
F. Licci
Keyword(s):  
High Temperature ◽  
Critical Current Density ◽  
Single Crystals ◽  
Critical Current ◽  
Current Density ◽  
Large Scale ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Superconducting Transition ◽  
Theoretical Understanding

The discovery of high temperature superconductivity (HTSC) in oxide compounds has confronted materials scientists with many challenging problems. These include the preparation of ceramic samples with critical current density of about 106 A/cm2 at 77 K and sufficient mechanical strength for large-scale electrotechnical and magnetic applications and the preparation of epitaxial thin films of high structural perfection for electronic devices.The main interest in the growth of single crystals is for the study of physical phenomena, which will help achieve a theoretical understanding of HTSC. Theorists still do not agree on the fundamental mechanisms of HTSC, and there is a need for good data on relatively defect-free materials in order to test the many models. In addition, the study of the role of defects like twins, grain boundaries, and dislocations in single crystals is important for understanding such parameters as the critical current density. The study of HTSC with single crystals is also expected to be helpful for finding optimum materials for the various applications and hopefully achieving higher values of the superconducting transition temperature Tc than the current maximum of about 125 K. It seems unlikely at present that single crystals will be used in commercial devices, but this possibility cannot be ruled out as crystal size and quality improve.

Cuprate High Temperature Superconductors and the Vision for Room Temperature Superconductivity

SPIN ◽  
2017 ◽  
Vol 07 (02) ◽  
pp. 1750006 ◽  
Author(s):  
Dennis M. Newns ◽  
Glenn J. Martyna ◽  
Chang C. Tsuei
Keyword(s):  
High Temperature ◽  
High Frequency ◽  
Room Temperature ◽  
Phonon Frequency ◽  
High Temperature Superconductors ◽  
Low Frequency ◽  
Unconventional Superconductivity ◽  
Superconducting Transition ◽  
Strongly Coupled ◽  
Room Temperature Superconductivity

Superconducting transition temperatures of 164 K in cuprate high temperature superconductors (HTS) and recently 200 K in H3S under high pressure encourage us to believe that room temperature superconductivity (RTS) might be possible. In considering paths to RTS, we contrast conventional (BCS) SC, such as probably manifested by H3S, with the unconventional superconductivity (SC) in the cuprate HTS family. Turning to SC models, we show that in the presence of one or more van Hove singularities (vHs) near the Fermi level, SC mediated by classical phonons ([Formula: see text]phonon frequency) can occur. The phonon frequency in the standard [Formula: see text] formula is replaced by an electronic cutoff, enabling a much higher [Formula: see text] independent of phonon frequency. The resulting [Formula: see text] and isotope shift plot versus doping strongly resembles that seen experimentally in HTS. A more detailed theory of HTS, which involves mediation by classical phonons, satisfactorily reproduces the chief anomalous features characteristic of these materials. We propose that, while a path to RTS through an H3S-like scenario via strongly-coupled ultra-high frequency phonons is attractive, features perhaps unavailable at ordinary pressures, a route involving SC mediated by classical phonons which can be low frequency may be found.

HIGH TEMPERATURE SUPERCONDUCTIVITY IN Y-Ba-Cu-Nb-O SYSTEM

1988 ◽  
Vol 02 (03n04) ◽  
pp. 435-441 ◽  
Author(s):  
N. G. SURESHA ◽  
S. HIGO ◽  
Y. HAKURAKU ◽  
T. OTAWA ◽  
Y. HONJO ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
High Temperature ◽  
Powder Diffraction ◽  
High Temperature Superconductivity ◽  
Gradual Change ◽  
Transition Temperatures ◽  
Superconducting Transition ◽  
Oxide Superconductor ◽  
X Ray ◽  
Diffraction Patterns

Results of the resistivity and magnetic susceptibility measurements for an oxide superconductor with nominal compositions of Y 1 Ba 2( Cu 1−x Nb x)3 O 6+δ and Y 0.4 Ba 0.6 ( Cu 1−x Nb x) O 2+δ where x = 0.1, 0.15, 0.2, are reported. Superconducting transition temperatures, T c onset (T co ) and T c final (T cf ) are above 90 K and 80 K respectively. We have observed a gradual change in the X-ray powder diffraction patterns of the samples with the change in x.

High-temperature superconductivity in transition metallic hydrides MH11 (M = Mo, W, Nb, and Ta) under high pressure

2021 ◽  
Vol 23 (11) ◽  
pp. 6717-6724
Author(s):  
Mingyang Du ◽  
Zihan Zhang ◽  
Hao Song ◽  
Hongyu Yu ◽  
Tian Cui ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Transition Temperature ◽  
Critical Temperature ◽  
Superconducting Transition Temperature ◽  
High Temperature Superconductivity ◽  
Superconducting Transition ◽  
Optical Phonons ◽  
Acoustic Phonons ◽  
Acoustic Modes

The contribution of optical and acoustic modes to the superconducting transition temperature. The calculated EPC parameter λ, critical temperature (Tc), critical temperature caused by the interaction of electrons with optical phonons (T0c) and acoustic phonons (Tacc).

scholarly journals High-temperature superconductivity on the verge of a structural instability in lanthanum superhydride

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Dan Sun ◽  
Vasily S. Minkov ◽  
Shirin Mozaffari ◽  
Ying Sun ◽  
Yanming Ma ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperature Superconductivity ◽  
Experimental Studies ◽  
Structural Instability ◽  
High Symmetry ◽  
Superconducting Transition ◽  
Metallic Hydrogen ◽  
Key Factors ◽  
Structural Distortions ◽  
The 1960S

AbstractThe possibility of high, room-temperature superconductivity was predicted for metallic hydrogen in the 1960s. However, metallization and superconductivity of hydrogen are yet to be unambiguously demonstrated and may require pressures as high as 5 million atmospheres. Rare earth based “superhydrides”, such as LaH10, can be considered as a close approximation of metallic hydrogen even though they form at moderately lower pressures. In superhydrides the predominance of H-H metallic bonds and high superconducting transition temperatures bear the hallmarks of metallic hydrogen. Still, experimental studies revealing the key factors controlling their superconductivity are scarce. Here, we report the pressure and magnetic field dependence of the superconducting order observed in LaH10. We determine that the high-symmetry high-temperature superconducting Fm-3m phase of LaH10 can be stabilized at substantially lower pressures than previously thought. We find a remarkable correlation between superconductivity and a structural instability indicating that lattice vibrations, responsible for the monoclinic structural distortions in LaH10, strongly affect the superconducting coupling.

scholarly journals Is There a Metamaterial Route to High Temperature Superconductivity?

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Igor I. Smolyaninov ◽  
Vera N. Smolyaninova
Keyword(s):  
High Temperature ◽  
Critical Temperature ◽  
Dielectric Response ◽  
High Temperature Superconductivity ◽  
Traditional Approach ◽  
Spatial Scales ◽  
Superconducting Transition ◽  
Superconducting Coherence Length ◽  
Electromagnetic Metamaterials ◽  
Electron Interactions

Superconducting properties of a material such as electron-electron interactions and the critical temperature of superconducting transition can be expressed via the effective dielectric response functionεeff(q,ω) of the material. Such a description is valid on the spatial scales below the superconducting coherence length (the size of the Cooper pair), which equals ∼100 nm in a typical BCS superconductor. Searching for natural materials exhibiting larger electron-electron interactions constitutes a traditional approach to high temperature superconductivity research. Here we point out that recently developed field of electromagnetic metamaterials deals with somewhat related task of dielectric response engineering on sub-100 nm scale. We argue that the metamaterial approach to dielectric response engineering may considerably increase the critical temperature of a composite superconductor-dielectric metamaterial.

scholarly journals Isotope Effect in the Translation-Invariant Bipolaron Theory of High-Temperature Superconductivity

2020 ◽  
Vol 5 (4) ◽  
pp. 80
Author(s):  
Victor D. Lakhno
Keyword(s):  
High Temperature ◽  
Isotope Effect ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Superconducting Transition ◽  
Strong Electron ◽  
Translation Invariant ◽  
Electron Phonon Interaction ◽  
Theory Of Superconductivity

It is shown that the translation-invariant bipolaron theory of superconductivity can explain the dependence of the isotope coefficient in high-temperature superconductors on the critical temperature of a superconducting transition: in the case of strong electron–phonon interaction, the isotope coefficient is low when doping is optimal and high when it is weak. It is demonstrated that in the case of London penetration depth, the absolute value of the isotope coefficient behaves in the opposite way. A conclusion of the great role of non-adiabaticity in the case of weak doping is made. The criteria for d-wave phonon input into the isotope effect is established.

PHONON SPECTRUM AND THE ELASTIC CONSTANTS OF HIGH TcBa2YCu3O7

1988 ◽  
Vol 02 (06) ◽  
pp. 811-817 ◽  
Author(s):  
H.C. GUPTA
Keyword(s):  
High Temperature ◽  
Transition Temperature ◽  
Elastic Constants ◽  
Phonon Spectrum ◽  
High Temperature Superconductivity ◽  
Force Model ◽  
Superconducting Transition ◽  
Optical Phonons ◽  
Infra Red ◽  
Zone Centre

The phonon spectrum and the elastic constants of high superconducting transition temperature compound Ba2YCu3O7 have been investigated in both the tetragonal and the orthorhombic phases using an angular force model. The zone centre phonons agree well with the Raman and the infra-red measurements in the case of tetragonal phase as compared to the orthorhombic one. The acoustical phonons exhibit phonon anomalies in both the tetragonal and the orthorhombic structures. Number of optical phonons do not show dispersion in [ooq] direction indicating strong 2-dimensional features. The relevance of the phonons to the high temperature superconductivity is discussed. The elastic constants do not indicate anisotropy in either of the tetragonal or the orthorhombic phases.

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