Type
Text
Type
Dissertation
Advisor
Stephens, Peter | Petrovic, Cedomir | Verbaarschot, Jacobus | Khalid, Syed.
Date
2014-12-01
Keywords
Condensed matter physics | Superconductivity
Department
Department of Physics.
Language
en_US
Source
This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.
Identifier
http://hdl.handle.net/11401/76725
Publisher
The Graduate School, Stony Brook University: Stony Brook, NY.
Format
application/pdf
Abstract
Iron-based superconductor KxFe2-ySe2 has generated considerable attention having higher critical temperature (~31 K)* than previously reported FeSe series (~8 K) and showing a unique phase separation with Fe vacancy order. We investigate the effect of the chemical substitution to the ground state and report various ground states such as spin glass phase and superconductor-insulator transition (SIT) under high-magnetic field by substitution of Na, Te, and Ni on KxFe2-ySe2 single crystal. The normal-state in-plane resistivity below Tc and the upper critical field for KxFe2-ySe1.85Te0.15 and K0.50Na0.24Fe2-ySe2 are measured by suppressing superconductivity in pulsed magnetic fields. The normal-state resistivity is found to increase logarithmically as T/Tc goes to 0 with decreasing temperature similar to granular superconductors and Cu-based high-Tc superconductors. Our results suggest that SIT may be induced in high magnetic fields, which is related to the intrinsic real space phase separated states. We also present a ground state change of KxFe2-d-yNiySe2 (0.06
Recommended Citation
Ryu, Hyejin, "Phase separation and neighboring ground states of superconductivity in KxFe2− ySe2" (2014). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 2606.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/2606