CHANGES IN THE SUPERCONDUCTING PROPERTIES OF HIGH-Tc CUPRATES PRODUCED BY APPLIED ELECTRIC FIELDS

1992 ◽  
Vol 06 (10) ◽  
pp. 555-571 ◽  
Author(s):  
J. MANNHART
Keyword(s):  
Transport Properties ◽  
Electric Fields ◽  
Superconducting State ◽  
Experimental Studies ◽  
Charge Carriers ◽  
Superconducting Properties ◽  
Mobile Charge ◽  
High Tc ◽  
High Tc Cuprates

By changing the concentration of mobile charge carriers, applied electric fields influence the transport properties of high-T c superconductors in the superconducting state. Experimental studies of these effects are briefly reviewed.

scholarly journals Bulk and Single Crystal Growth Progress of Iron-Based Superconductors (FBS): 1111 and 1144

Crystals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 20
Author(s):  
Shiv J. Singh ◽  
Mihai I. Sturza
Keyword(s):  
Crystal Growth ◽  
Experimental Studies ◽  
Short Review ◽  
Single Crystal Growth ◽  
Superconducting Properties ◽  
High Quality ◽  
Iron Based Superconductors ◽  
High Tc ◽  
Developmental Issues ◽  
Iron Based

The discovery of iron-based superconductors (FBS) and their superconducting properties has generated huge research interest and provided a very rich physics high Tc family for fundamental and experimental studies. The 1111 (REFeAsO, RE = Rare earth) and 1144 (AEAFe4As4, AE = Ca, Eu; A = K, Rb) families are the two most important families of FBS, which offer the high Tc of 58 K and 36 K with doping and without doping, respectively. Furthermore, the crystal growth of these families is not an easy process, and a lot of efforts have been reported in this direction. However, the preparation of high-quality and suitable-sized samples is still challenging. In this short review, we will summarize the growth of materials with their superconducting properties, especially polycrystals and single crystals, for the 1111 and 1144 families, and make a short comparison between them to understand the developmental issues.

scholarly journals Unusual metallic conductivity of high-Tc cuprates

2021 ◽  
Vol 5 (3) ◽  
pp. 183-191
Author(s):  
S. Dzhumanov ◽  
Sh.R. Malikov ◽  
Sh.S. Djumanov
Keyword(s):  
Transport Theory ◽  
Charge Carriers ◽  
Cooper Pairs ◽  
Linear Temperature Dependence ◽  
Linear Temperature ◽  
High Tc ◽  
Distinctive Features ◽  
Metallic Conductivity ◽  
Temperature Dependences ◽  
High Tc Cuprates

The intrinsic mechanisms of the unusual metallic transports of three types of relevant charge carriers (large polarons, excited (dissociated) polaronic components of bosonic Cooper pairs and bosonic Cooper pairs themselves) along the CuO2 layers of high-Tc cuprates are identified and the new features of metallic conductivity in the CuO2 layers (i.e. ab -planes) of underdoped and optimally doped cuprates are explained. The in-plane conductivity of high-Tc cuprates is associated with the metallic transports of such charge carriers at their scattering by lattice vibrations in thin CuO2 layers. The proposed charge transport theory in high-Tc cuprates allows to explain consistently the distinctive features of metallic conductivity and the puzzling experimental data on the temperature dependences of their in-plane resistivity pab. In underdoped and optimally doped cuprates the linear temperature dependence of pab(T) above the pseudogap formation temperature T∗ is associated with the scattering of polaronic carriers at acoustic and optical phonons, while the different (upward and downward) deviations from the linearity in pab(T) below T∗ are caused by the pseudogap effect on the conductivity of the excited Fermi components of bosonic Cooper pairs and by the dominating conductivity of bosonic Cooper pairs themselves in the normal state of these high-Tc materials.

scholarly journals Superconductivity in HEA-Type Compounds

2021 ◽  
Author(s):  
Yoshikazu Mizuguchi ◽  
Aichi Yamashita
Keyword(s):  
Layered Compounds ◽  
High Entropy Alloy ◽  
Synthesis Methods ◽  
Superconducting Properties ◽  
High Tc ◽  
High Entropy ◽  
Type Transition ◽  
Structural Dimensionality ◽  
Crystal Structural ◽  
High Tc Cuprates

Since the discovery of superconductivity in a high-entropy alloy (HEA) Ti-Zr-Nb-Hf-Ta in 2014, the community of superconductor science has explored new HEA superconductors to find the merit of the HEA states on superconducting properties. Since 2018, we have developed “HEA-type” compounds as superconductors or thermoelectric materials. As well known, compounds like intermetallic compounds or layered compounds are composed of multi crystallographic sites. In a HEA-type compounds, one or more sites are alloyed and total mixing entropy satisfies with the criterion of HEA. Herein, we summarize the synthesis methods, the crystal structural variation and superconducting properties of the HEA-type compounds, which include NaCl-type metal tellurides, CuAl2-type transition metal zirconides, high-Tc cuprates, and BiS2-based layered superconductors. The effects of the introduction of a HEA site in various kinds of complicated compounds are discussed from the structural-dimensionality viewpoint.

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