| 1. |
|
|
| 2. |
|
|
| 3. |
- Grinenko, V., et al.
(författare)
-
State with spontaneously broken time-reversal symmetry above the superconducting phase transition
- 2021
-
Ingår i: Nature Physics. - : Springer Nature. - 1745-2473 .- 1745-2481. ; 17:11, s. 1254-1259
-
Tidskriftsartikel (refereegranskat)abstract
- The most well-known example of an ordered quantum state—superconductivity—is caused by the formation and condensation of pairs of electrons. Fundamentally, what distinguishes a superconducting state from a normal state is a spontaneously broken symmetry corresponding to the long-range coherence of pairs of electrons, leading to zero resistivity and diamagnetism. Here we report a set of experimental observations in hole-doped Ba1−xKxFe2As2. Our specific-heat measurements indicate the formation of fermionic bound states when the temperature is lowered from the normal state. However, when the doping level is x ≈ 0.8, instead of the characteristic onset of diamagnetic screening and zero resistance expected below the superconducting phase transition, we observe the opposite effect: the generation of self-induced magnetic fields in the resistive state, measured by spontaneous Nernst effect and muon spin rotation experiments. This combined evidence indicates the existence of a bosonic metal state in which Cooper pairs of electrons lack coherence, but the system spontaneously breaks time-reversal symmetry. The observations are consistent with the theory of a state with fermionic quadrupling, in which long-range order exists not between Cooper pairs but only between pairs of pairs.
|
|
| 4. |
- Sagalowicz, Laurent, et al.
(författare)
-
Structure of the wafer fused InP (001)-GaAs (001) interface
- 1997
-
Ingår i: Philosophical Magazine Letters. - : Informa UK Limited. - 0950-0839 .- 1362-3036. ; 76:6, s. 445-452
-
Tidskriftsartikel (refereegranskat)abstract
- A structural study of wafer fused InP-GaAs interfaces has been carried out. The geometry of the dislocation network which accommodates the twist and the lattice mismatch is first given using a geometrical approach. Cross-sectional transmission electron microscopy and plan view observations are presented. Two different misfit cases are observed. (1) When no twist is present, the 3.7% lattice mismatch is relaxed by a regular square network of dislocations with pure edge character. (2) When an additional twist is present, a square network of dislocations results as well but here the dislocations have a mixed character; 60° dislocations are also observed, some form closed defect circuits and others very likely accommodate a small tilt. The interaction between the 60° dislocations and the edge dislocations is explained in detail. Voids or inclusions are also observed as well as additional dislocations which may accommodate part of the thermal mismatch. © 1997 Taylor & Francis Ltd.
|
|
