MgB2涡旋液体相研究  

STUDY ON MgB_2 VORTEX LIQUID PHASE

作　　者：韩永胜[1,2] 袁国秋[1] 俞力[1] 顾大伟[3] 徐小农[1] 卢定伟[1] 沈临江[3] 金新[1] 

机构地区：[1]南京大学物理系,固体微结构实验室,南京210093 [2]中国药科大学、基础科学部,南京210009 [3]南京工业大学物理系,南京210009

出　　处：《低温物理学报》2003年第A01期59-63,共5页Low Temperature Physical Letters

摘　　要：近来几个超导研究小组相继报导MgB2 磁通线的涡旋相图具有与高温超导体相似的特性 ,而且该超导体电阻率在外场中展宽的超导区大部份对应涡旋液体相 .本文发展了一种新的求导超导体有效钉扎势方法 ,并利用MgB2 电阻在外场中展宽测量数据 ,发现在超导转变区 ,其有效钉扎势相应温度的函数关系分为两个区域 ,其中一个区的热激活能和温度的关系是线性的 ,另外一个区是非线性的 .这明确表明与F.Bouquetetal(Nature,41 1 (2 0 0 1 ) ,448)发现高温超导体YBa2 Cu3 O7-δ具有两个涡旋液体相相类似 .MgB2 的涡旋液体相也同样具有两个不同的液体相.The recent reports by several research groups show that the vortex liquid phase of MgB-2 is the same as High Temperature Superconductivity. The most superconduct region of resistance broadening in applied fields of MgB-2 is in vortex liquid phase. we proposed a new mathematical treatment on resistance broadening in applied fields to study the effective pinning potential U-{eff} of the vortex liquid phase of MgB-2. We find that the relationship between U-{eff} and Temperature (T) is separated into two regions, one is linear dependent (U-{eff}～(T-c-T)), the other is nonlinear dependent. These findings disclosure clearly that the vortex liquid of MgB-2 has two phases, which corresponds to the discovery in HTSC YBa-2Cu-3O-{7-δ} by F. Bouquet et al (Nature, 411(2001), 448).

关 键 词：二硼化镁超导体 涡旋相图 涡旋液体 有效钉扎势法 热激活能 磁滞回线测量 

分 类 号：O511[理学—低温物理]