Experimental Proof of a Time-Reversal-Invariant Order Parameter with aπshift inYBa2Cu3O7−δ

1995 ◽  
Vol 74 (22) ◽  
pp. 4523-4526 ◽  
Author(s):  
A. Mathai ◽  
Y. Gim ◽  
R. C. Black ◽  
A. Amar ◽  
F. C. Wellstood
Keyword(s):  
Time Reversal ◽  
Order Parameter ◽  
Experimental Proof ◽  
Invariant Order

scholarly journals Unsplit superconducting and time reversal symmetry breaking transitions in Sr2RuO4 under hydrostatic pressure and disorder

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Vadim Grinenko ◽  
Debarchan Das ◽  
Ritu Gupta ◽  
Bastian Zinkl ◽  
Naoki Kikugawa ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Symmetry Breaking ◽  
Time Reversal ◽  
Order Parameter ◽  
Muon Spin Rotation ◽  
Horizontal Line ◽  
Time Reversal Symmetry ◽  
Zero Field ◽  
Symmetry Protected ◽  
Line Node

AbstractThere is considerable evidence that the superconducting state of Sr2RuO4 breaks time reversal symmetry. In the experiments showing time reversal symmetry breaking, its onset temperature, TTRSB, is generally found to match the critical temperature, Tc, within resolution. In combination with evidence for even parity, this result has led to consideration of a dxz ± idyz order parameter. The degeneracy of the two components of this order parameter is protected by symmetry, yielding TTRSB = Tc, but it has a hard-to-explain horizontal line node at kz = 0. Therefore, s ± id and d ± ig order parameters are also under consideration. These avoid the horizontal line node, but require tuning to obtain TTRSB ≈ Tc. To obtain evidence distinguishing these two possible scenarios (of symmetry-protected versus accidental degeneracy), we employ zero-field muon spin rotation/relaxation to study pure Sr2RuO4 under hydrostatic pressure, and Sr1.98La0.02RuO4 at zero pressure. Both hydrostatic pressure and La substitution alter Tc without lifting the tetragonal lattice symmetry, so if the degeneracy is symmetry-protected, TTRSB should track changes in Tc, while if it is accidental, these transition temperatures should generally separate. We observe TTRSB to track Tc, supporting the hypothesis of dxz ± idyz order.

scholarly journals Natural Time Analysis of Seismicity within the Mexican Flat Slab before the M7.1 Earthquake on 19 September 2017

Entropy ◽  
2020 ◽  
Vol 22 (7) ◽  
pp. 730 ◽  
Author(s):  
E. Leticia Flores-Márquez ◽  
Alejandro Ramírez-Rojas ◽  
Jennifer Perez-Oregon ◽  
N. V. Sarlis ◽  
E. S. Skordas ◽  
...  
Keyword(s):  
Time Reversal ◽  
Order Parameter ◽  
Pacific Coast ◽  
Entropy Change ◽  
North American Plate ◽  
Cocos Plate ◽  
Mexican Pacific ◽  
Flat Slab ◽  
The North ◽  
Natural Time

One of the most important subduction zones in the world is located in the Mexican Pacific Coast, where the Cocos plate inserts beneath the North American plate. One part of it is located in the Mexican Pacific Coast, where the Cocos plate inserts beneath the North American plate with different dip angles, showing important seismicity. Under the central Mexican area, such a dip angle becomes practically horizontal and such an area is known as flat slab. An earthquake of magnitude M7.1 occurred on 19 September 2017, the epicenter of which was located in this flat slab. It caused important human and material losses of urban communities including a large area of Mexico City. The seismicity recorded in the flat slab region is analyzed here in natural time from 1995 until the occurrence of this M7.1 earthquake in 2017 by studying the entropy change under time reversal and the variability β of the order parameter of seismicity as well as characterize the risk of an impending earthquake by applying the nowcasting method. The entropy change ΔS under time reversal minimizes on 21 June 2017 that is almost one week after the observation of such a minimum in the Chiapas region where a magnitude M8.2 earthquake took place on 7 September 2017 being Mexico’s largest quake in more than a century. A minimum of β was also observed during the period February–March 2017. Moreover, we show that, after the minimum of ΔS, the order parameter of seismicity starts diminishing, thus approaching gradually the critical value 0.070 around the end of August and the beginning of September 2017, which signals that a strong earthquake is anticipated shortly in the flat slab.

THE FASCINATING NEW PHYSICS OF SOME OLD BCS SUPERCONDUCTORS

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3134-3139
Author(s):  
V. BARZYKIN
Keyword(s):  
Time Reversal ◽  
Order Parameter ◽  
Coulomb Repulsion ◽  
New Physics ◽  
Superconducting Order Parameter ◽  
High Symmetry ◽  
New Materials ◽  
S Wave ◽  
Orbital Magnetism ◽  
Complicated Mechanism

We consider the pairing state due to the usual Bardeen-Cooper-Schrieffer mechanism in substances where the Fermi surface forms pockets around several points of high symmetry. The symmetry imposed on the multiple pocket positions can give rise to a multidimensional nontrivial superconducting order parameter. A complicated mechanism is not required for unusual superconductivity to exist, just the usual phonon attraction and Coulomb repulsion. Time reversal symmetry is broken, so the superconducting state also has orbital magnetism. In some sense, these superconductors are similar to superfluid3 He, which is known to have an 18-dimensional order parameter and a complicated phase diagram. We suggest several candidate substances where ordering of this kind may appear and discuss how these phases may be identified. Superconductivity in these new materials is expected to be much less sensitive to impurities than in other non s-wave superconductors.1

scholarly journals TIME REVERSAL BREAKING SUPERCONDUCTING STATE IN THE PHASE DIAGRAM OF THE CUPRATES

2003 ◽  
Vol 17 (04n06) ◽  
pp. 614-620 ◽  
Author(s):  
G. SANGIOVANNI ◽  
M. CAPONE ◽  
S. CAPRARA
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Order Phase Transition ◽  
Superconducting State ◽  
Time Reversal ◽  
Low Temperatures ◽  
Order Parameter ◽  
Andreev Reflection ◽  
Previous Analysis ◽  
Second Order Phase Transition

We review and extend a previous study1 on the symmetry of the superconducting state, stimulated by recent tunneling and Andreev reflection measurements giving robust evidences for the existence of a dx2-y2 + idxy order parameter in the overdoped regime of two different cuprates. Looking for a possible second-order phase transition from a standard dx2-y2 to a mixed and time reversal breaking state, we confirm the results of our previous analysis on La 2-x Sr x CuO 4. In the case of Y 1-y Ca y Ba 2 Cu 3 O 7-x as well, among all the allowed symmetries, the dx2 - y2 + idxy is the most favored one and the unconventional state is likely to occur in a small dome of the phase diagram located in the optimal-overdoped region and at very low temperatures.

MAGNETIC TESTS TO REVEAL TRIPLET SUPERCONDUCTIVITY IN (TMTSF)2PF6 AND A POSSIBLE BREAKING OF A TIME REVERSAL SYMMETRY IN Sr2RuO4, LBCO, and YBCO

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3198-3198
Author(s):  
A. G. LEBED
Keyword(s):  
Time Reversal ◽  
Order Parameter ◽  
Time Reversal Symmetry ◽  
Spin Part ◽  
Two Component ◽  
D Wave

We propose methods to reveal the existence of a two-component triplet order parameter (which is recently suggested to break a time reversal symmetry in Sr 2 RuO 4) and to test a possible two-component singlet d-wave order parameter in high- T c superconductors (which may also break the time reversal symmetry). We have also determined a spin part (i.e., d(k) = [dx(k) ≠ 0, dy(k) = 0, dz(k) = 0)] of a triplet order parameter1,2 in (TMTSF) 2 PF 6 under pressure by means of an analysis of the experimental H c2 measurements (I. J. Lee et al., Phys. Rev. Lett. 78, 3555 (1997)).

scholarly journals Spin-orbit scattering in dx2-y2 superconductors

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3513-3515 ◽  
Author(s):  
M. J. Graf ◽  
A. V. Balatsky ◽  
J. A. Sauls
Keyword(s):  
Magnetic Field ◽  
Time Reversal ◽  
Order Parameter ◽  
Magnetic Impurity ◽  
Time Reversal Symmetry ◽  
Spin Orbit

We show that spin-orbit scattering off an isolated magnetic impurity in a singlet dx2-y2 superconductor generates a dxy order parameter with locally broken time-reversal symmetry. A consequence of the induced dxy component are orbital charge currents and a magnetic field in the vicinity of the magnetic impurity.

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