start-ver=1.4
cd-journal=joma
no-vol=97
cd-vols=
no-issue=9
article-no=
start-page=094505
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2018
dt-pub=20180309
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Pressure dependence of superconductivity in low- and high-T-c phases of (NH3)(y)NaxFeSe
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract= We prepared two superconducting phases, which are called “low-Tc phase” and “high-Tc phase” of (NH3)yNaxFeSe showing Tc’s of 35 and 44 K, respectively, at ambient pressure, and studied the superconducting behavior and structure of each phase under pressure. The Tc of the 35 K at ambient pressure rapidly decreases with increasing pressure up to 10 GPa, and it remains unchanged up to 22 GPa. Finally, superconductivity was not observed down to 1.4 K at 29 GPa, i.e., Tc < 1.4K. The Tc of the 44 K phase also shows a monotonic decrease up to 15 GPa and it weakly decreases up to 25 GPa. These behaviors suggest no pressure-driven high-Tc phase (called “SC-II”) between 0 and 25 GPa for the low-Tc and high-Tc phases of (NH3)yNaxFeSe, differing from the behavior of (NH3)yCsxFeSe,which has a pressure-driven high-Tc phase (SC-II) in addition to the superconducting phase (SC-I) observed at ambient and low pressures. The Tc-c phase diagram for both low-Tc and high-Tc phases shows that the Tc can be linearly scaled with c (or FeSe plane spacing), where c is a lattice constant. The reason why a pressure-driven high-Tc phase (SC-II) was found for neither low-Tc nor high-Tc phases of (NH3)yNaxFeSe is fully discussed, suggesting a critical c value as the key to forming the pressure-driven high-Tc phase (SC-II). Finally, the precise Tc-c phase diagram is depicted using the data obtained thus far from FeSe codoped with a metal and NH3 or amine, indicating two distinct Tc-c lines below c = 17.5A° .
en-copyright=
kn-copyright=

en-aut-name=TeraoTakahiro
en-aut-sei=Terao
en-aut-mei=Takahiro
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=YangXiaofan
en-aut-sei=Yang
en-aut-mei=Xiaofan
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=MiaoXiao
en-aut-sei=Miao
en-aut-mei=Xiao
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=ZhengLu
en-aut-sei=Zheng
en-aut-mei=Lu
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=GotoHidenori
en-aut-sei=Goto
en-aut-mei=Hidenori
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

en-aut-name=MiyazakiTakafumi
en-aut-sei=Miyazaki
en-aut-mei=Takafumi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=

en-aut-name=YamaokaHitoshi
en-aut-sei=Yamaoka
en-aut-mei=Hitoshi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=7
ORCID=

en-aut-name=IshiiHirofumi
en-aut-sei=Ishii
en-aut-mei=Hirofumi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=8
ORCID=

en-aut-name=LiaoYen-Fa
en-aut-sei=Liao
en-aut-mei=Yen-Fa
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=9
ORCID=

en-aut-name=KubozonoYoshihiro
en-aut-sei=Kubozono
en-aut-mei=Yoshihiro
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=10
ORCID=

affil-num=1
en-affil=Research Institute for Interdisciplinary Science, Okayama University
kn-affil=

affil-num=2
en-affil=Research Institute for Interdisciplinary Science, Okayama University
kn-affil=

affil-num=3
en-affil=Research Institute for Interdisciplinary Science, Okayama University
kn-affil=

affil-num=4
en-affil=Research Institute for Interdisciplinary Science, Okayama University
kn-affil=

affil-num=5
en-affil=Research Institute for Interdisciplinary Science, Okayama University
kn-affil=

affil-num=6
en-affil=Research Laboratory for Surface science, Okayama University
kn-affil=

affil-num=7
en-affil=RIKEN SPring-8 Center
kn-affil=

affil-num=8
en-affil=National Synchrotron Radiation Research Center
kn-affil=

affil-num=9
en-affil=National Synchrotron Radiation Research Center
kn-affil=

affil-num=10
en-affil=Research Institute for Interdisciplinary Science, Okayama University
kn-affil=
en-keyword=Superconductors
kn-keyword=Superconductors
en-keyword=2-dimensional systems
kn-keyword=2-dimensional systems
en-keyword=4-terminal techniques
kn-keyword=4-terminal techniques
en-keyword=Pressure effects
kn-keyword=Pressure effects
en-keyword=X-ray diffraction
kn-keyword=X-ray diffraction
END