Induced first-order transition inside superconducting state by metamagnetism in an easy-axis magnetic field on UTe

Tokiwa, Yoshifumi  ; Opletal, P.  ; Sakai, Hironori   ; Yamamoto, Etsuji  ; Kambe, Shinsaku  ; Tokunaga, Yo  ; Haga, Yoshinori   ; Kimata, Motoi*; Awaji, Satoshi*; Sasaki, Takahiko*; Aoki, Dai*; Kubo, Katsunori 

In unconventional superconductivity, magnetism is considered to be the origin of the superconducting interaction, and the relationship between magnetism and superconductivity is a central theme of research. UTe has attracted much attention due to its potential for reentrant superconductivity and spin-triplet superconductivity in magnetic fields. In this material, when a magnetic field is applied along the a-axis, a weak metamagnetism occurs near 6T due to Fermi surface instability. In the initial crystals synthesized by the vapor phase epitaxy, superconductivity disappeared in the magnetic field where metamagnetism was generated because = 1.6K and upper critical magnetic field = 6T, and superconductivity was not affected. In the pure single crystal synthesized by the molten salt flux method, =2.1K is 25% stronger than the initial while =12T is doubled. In this study, we revealed that this metamagnetism enhances .