Peak Effect and Vortex Line Lattice Melting in Single Crystalline YNi2B2C

K. Hirata；H. Takeya；S. Miyamoto；T. Mochiku；K. Togano

Chinese Journal of Physics

36卷2S期（1998 / 04 / 01）

215 - 221

英文

Anomalous magnetic behavior has been studied on single crystalline YNi2B2C by dc-magnetization and ac-susceptibility measurements. Peak effect has been found in the reversibility region close to the upper critical field Hc2(T) by dc-magnetization and ac-susceptibility. The peak effect observed by dc-magnetization is ceased at about 18 kOe and 11 K with decreasing magnetic field parallel to the c-axis and increasing temperature. However, in ac-susceptibility, a sharp dip structure is still observed to about 5 kOe and 13.3 K, instead of the broad one at the higher magnetie fields of the peak effect region than about 15 kOe. A magnetic phase diagram of YNi2B2C has been established. From the characteristic features of the peek effect, it is speculated as a universal feature in almost isotropic superconductors with weak pinning centers that the transition from the peak effect (accompanied with the vortex glass melting) to the vortex lattice melting occurs successively with decreasing magnetic field and increasing temperature.