Konczykowski M, van der Beek C J, Koshelev A E, Mosser V, Dodgson M, Kes P H
Laboratoire des Solides Irradiés, CNRS-UMR 7642 & CEA/DSM/DRECAM, Ecole Polytechnique, Palaiseau, France.
Phys Rev Lett. 2006 Dec 8;97(23):237005. doi: 10.1103/PhysRevLett.97.237005. Epub 2006 Dec 7.
Precision measurements of the vortex phase diagram in single crystals of the layered superconductor Bi2Sr2CaCu2O8+delta in oblique magnetic fields confirm the existence of a second phase transition, in addition to the usual first-order vortex-lattice melting line Hm(T). The transition has a strong first-order character, is accompanied by strong hysteresis, and intersects the melting line in a tricritical point (Hm perpendicular, Hcr parallel). Its field dependence and the changing character of the melting line at the tricritical point strongly suggest that the ground state for magnetic fields closely aligned with the superconducting layers is a lattice of uniformly tilted vortex lines.
在倾斜磁场中对层状超导体Bi2Sr2CaCu2O8+δ单晶中的涡旋相图进行的精确测量证实，除了通常的一级涡旋晶格熔化线Hm(T)之外，还存在第二个相变。该转变具有很强的一级特征，伴有强烈的滞后现象，并在一个三临界点（Hm垂直，Hcr平行）与熔化线相交。其场依赖性以及三临界点处熔化线变化的特征强烈表明，与超导层紧密对齐的磁场的基态是均匀倾斜涡旋线的晶格。
