scholarly journals Spin susceptibility of charge-ordered YBa2Cu3Oy across the upper critical field

2017 ◽  
Vol 114 (50) ◽  
pp. 13148-13153 ◽  
Author(s):  
Rui Zhou ◽  
Michihiro Hirata ◽  
Tao Wu ◽  
Igor Vinograd ◽  
Hadrien Mayaffre ◽  
...  
Keyword(s):  
Long Range ◽  
Critical Field ◽  
Density Wave ◽  
Upper Critical Field ◽  
Spin Susceptibility ◽  
Copper Oxides ◽  
Superconducting Gap ◽  
Zero Field ◽  
Fermi Surface Reconstruction ◽  
Probe Measurements

The value of the upper critical field Hc2, a fundamental characteristic of the superconducting state, has been subject to strong controversy in high-Tc copper oxides. Since the issue has been tackled almost exclusively by macroscopic techniques so far, there is a clear need for local-probe measurements. Here, we use 17O NMR to measure the spin susceptibility χspin of the CuO2 planes at low temperature in charge-ordered YBa2Cu3Oy. We find that χspin increases (most likely linearly) with magnetic field H and saturates above field values ranging from 20 T to 40 T. This result is consistent with the lowest Hc2 values claimed previously and with the interpretation that the charge density wave (CDW) reduces Hc2 in underdoped YBa2Cu3Oy. Furthermore, the absence of marked deviation in χspin(H) at the onset of long-range CDW order indicates that this Hc2 reduction and the Fermi-surface reconstruction are primarily rooted in the short-range CDW order already present in zero field, not in the field-induced long-range CDW order. Above Hc2, the relatively low values of χspin at T= 2 K show that the pseudogap is a ground-state property, independent of the superconducting gap.

Coexistence of superconductivity and spin density wave orderings in Bechgaard and Fabre salts

2002 ◽  
Vol 12 (9) ◽  
pp. 197-200
Author(s):  
C. Pasquier ◽  
P. Auban-Senzier ◽  
T. Vuletic ◽  
S. Tomic ◽  
M. Heritier ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Spin Density ◽  
Critical Field ◽  
Density Wave ◽  
Spin Density Wave ◽  
Upper Critical Field ◽  
Small Range ◽  
Zero Field ◽  
Pressure Independent ◽  
Two Phases

In a small range of pressure, superconductivity (SC) and Spin Density Wave (SDW) states are shown to coexist in the Bechgaard salt (TMTSF)2PF6 and the Fabre salt (TMTTF)2BF4. In (TMTSF)2PF6, a precise investigation of the (P,T) phase diagram has led us to demonstrate the coexistence of the two phases with a superconducting critical temperature which is pressure independent while the critical current at zero field is strongly depressed as the pressure is decreased. In (TMTTF)2BF4, using non-linear transport measurements, we present the signature of the presence of 1D superconducting filaments in a small range of pressure. We also investigate the compound under a magnetic field applied along the c*-axis: the upper critical field is more or less pressure independent and is about 2 Tesla (at zero temperature). We suggest that such a high critical field is compatible with the penetration of the magnetic field in the insulating regions of the compound in a similar way of Josephson vortices in layered superconductors.

scholarly journals The Gap and the Upper Critical FieldHc2as Function of Doping for High-TcCuprates

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
S. Orozco ◽  
R. M. Méndez-Moreno ◽  
M. A. Ortiz
Keyword(s):  
High Temperature ◽  
Critical Field ◽  
Energy Gap ◽  
High Temperature Superconductors ◽  
Upper Critical Field ◽  
Superconducting Gap ◽  
Phonon Interaction ◽  
As Doping ◽  
Electron Phonon Interaction ◽  
Wave Symmetry

The relation between thed-wave superconducting gapΔ0and the specific heat obtained with the Volovik effect is used to determine the upper critical fieldHc2as doping function, for high-temperature superconductors. A two-components model withd-wave symmetry, within the BCS framework, is introduced to describe the superconducting state. Generalized Fermi surface topologies are used in order to increase the density of states at the Fermi level, allowing the high-Tcvalues observed. The electron-phonon interaction is considered the most relevant mechanism for the high-Tccuprates, where the available phonon energy is provided by the half-breathing modes. The energy gap valuesΔ0calculated with this model are introduced to describe the variation of the upper critical fieldHc2as function of doping, forLa2-xSrxCuO4.

scholarly journals Ideal charge-density-wave order in the high-field state of superconducting YBCO

2016 ◽  
Vol 113 (51) ◽  
pp. 14645-14650 ◽  
Author(s):  
H. Jang ◽  
W.-S. Lee ◽  
H. Nojiri ◽  
S. Matsuzawa ◽  
H. Yasumura ◽  
...  
Keyword(s):  
Charge Density ◽  
Critical Field ◽  
Ground State ◽  
Charge Density Wave ◽  
High Field ◽  
Cuprate Superconductors ◽  
Density Wave ◽  
Quantum Oscillation ◽  
Zero Field ◽  
Correlation Volume

The existence of charge-density-wave (CDW) correlations in cuprate superconductors has now been established. However, the nature of the CDW ground state has remained uncertain because disorder and the presence of superconductivity typically limit the CDW correlation lengths to only a dozen unit cells or less. Here we explore the field-induced 3D CDW correlations in extremely pure detwinned crystals of YBa2Cu3O2(YBCO) ortho-II and ortho-VIII at magnetic fields in excess of the resistive upper critical field (Hc2) where superconductivity is heavily suppressed. We observe that the 3D CDW is unidirectional and possesses a long in-plane correlation length as well as significant correlations between neighboring CuO2planes. It is significant that we observe only a single sharply defined transition at a critical field proportional toHc2, given that the field range used in this investigation overlaps with other high-field experiments including quantum oscillation measurements. The correlation volume is at least two to three orders of magnitude larger than that of the zero-field CDW. This is by far the largest CDW correlation volume observed in any cuprate crystal and so is presumably representative of the high-field ground state of an “ideal” disorder-free cuprate.

scholarly journals Upper critical field ofKFe2As2under pressure: A test for the change in the superconducting gap structure

2014 ◽  
Vol 89 (22) ◽  
Author(s):  
Valentin Taufour ◽  
Neda Foroozani ◽  
Makariy A. Tanatar ◽  
Jinhyuk Lim ◽  
Udhara Kaluarachchi ◽  
...  
Keyword(s):  
Critical Field ◽  
Upper Critical Field ◽  
Superconducting Gap ◽  
Gap Structure

Enhancement of critical temperature and upper critical field due to Nb substitution in Zr-V alloy superconductors

2020 ◽  
Author(s):  
Sabyasachi Paul ◽  
S. K. Ramjan ◽  
L. S. Sharath Chandra ◽  
Archna Sagdeo ◽  
M. K. Chattopadhyay
Keyword(s):  
Critical Temperature ◽  
Critical Field ◽  
Upper Critical Field

scholarly journals Experimental and theoretical analysis of the upper critical field in ferromagnet–superconductor–ferromagnet trilayers

2013 ◽  
Vol 26 (8) ◽  
pp. 085003 ◽  
Author(s):  
E Antropov ◽  
M S Kalenkov ◽  
J Kehrle ◽  
V I Zdravkov ◽  
R Morari ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Critical Field ◽  
Upper Critical Field

scholarly journals Superconductivity with High Upper Critical Field in the Cubic Centrosymmetric η-Carbide Nb4Rh2C1−δ

2021 ◽  
Author(s):  
KeYuan Ma ◽  
Karolina Gornicka ◽  
Robin Lefèvre ◽  
Yikai Yang ◽  
Henrik M. Rønnow ◽  
...  
Keyword(s):  
Critical Field ◽  
Upper Critical Field
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