title: Enhanced critical current density in the pressure-induced magnetic state of the high-temperature superconductor FeSe.
abstract: We investigate the relation of the critical current density (Jc) and the remarkably increased superconducting transition temperature (Tc) for the FeSe single crystals under pressures up to 2.43 GPa, where the Tc is increased by ~8 K/GPa. The critical current density corresponding to the free flux flow is monotonically enhanced by pressure which is due to the increase in Tc, whereas the depinning critical current density at which the vortex starts to move is more influenced by the pressure-induced magnetic state compared to the increase of Tc. Unlike other high-Tc superconductors, FeSe is not magnetic, but superconducting at ambient pressure. Above a critical pressure where magnetic state is induced and coexists with superconductivity, the depinning Jc abruptly increases even though the increase of the zero-resistivity Tc is negligible, directly indicating that the flux pinning property compared to the Tc enhancement is a more crucial factor for an achievement of a large Jc. In addition, the sharp increase in Jc in the coexisting superconducting phase of FeSe demonstrates that vortices can be effectively trapped by the competing antiferromagnetic order, even though its antagonistic nature against superconductivity is well documented. These results provide new guidance toward technological applications of high-temperature superconductors.
authors.affiliation: Department of Physics, Sungkyunkwan University, Suwon 440-746, Republic of Korea.
authors.forename: Soon-Gil
authors.initials: SG
authors.lastname: Jung
authors.affiliation: Department of Physics, Sungkyunkwan University, Suwon 440-746, Republic of Korea.
authors.forename: Ji-Hoon
authors.initials: JH
authors.lastname: Kang
authors.affiliation: Department of Physics, Sungkyunkwan University, Suwon 440-746, Republic of Korea.
authors.forename: Eunsung
authors.initials: E
authors.lastname: Park
authors.affiliation: Department of Physics, Sungkyunkwan University, Suwon 440-746, Republic of Korea.
authors.forename: Sangyun
authors.initials: S
authors.lastname: Lee
authors.affiliation: Institute of Physics, National Chiao Tung University, Hsinchu 30010, Taiwan.
authors.forename: Jiunn-Yuan
authors.initials: JY
authors.lastname: Lin
authors.affiliation: Institute of Experimental Mineralogy, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia.
authors.forename: Dmitriy A
authors.initials: DA
authors.lastname: Chareev
authors.affiliation: Low Temperature Physics and Superconductivity Department, Physics Faculty, Moscow State University, 119991 Moscow, Russia.|Theoretical Physics and Applied Mathematics Department, Institute of Physics and Technology, Ural Federal University, Ekaterinburg 620002, Russia.|National University of Science and Technology "MISiS", Moscow 119049, Russia.
authors.forename: Alexander N
authors.initials: AN
authors.lastname: Vasiliev
authors.affiliation: Department of Physics, Sungkyunkwan University, Suwon 440-746, Republic of Korea.
authors.forename: Tuson
authors.initials: T
authors.lastname: Park