双掺杂铁基1111型超导体Nd1-xBaxFeAsO1-2xF2x的磁传输性能研究  

ON MAGNETO-TRANSPORT PROPERITES FOR IRON-BASED 1111-TYPE Nd_(1-x)Ba_xFeAsO_(1-2x)F_(2x) WITH BINARY DOPING

作　　者：瞿淳清[1] 陈昌兆[1] 刘志勇[1] 鲁玉明[1] 蔡传兵[1] 

机构地区：[1]上海大学超导应用技术研究中心,上海大学物理系,上海200444

出　　处：《低温物理学报》2011年第6期401-405,共5页Low Temperature Physical Letters

基　　金：国家科技部973项目(批准号:2011CBA00105);863项目(批准号:2009AA03Z204);上海市重点学科(批准号:S30105)资助的课题~~

摘　　要：采用两步固相反应法,在母相FeAs-1111结构的NdFeAsO中掺入BaF2,实现电子与空穴的双掺杂.该体系超导转变温度(Tc)在33～50K范围,取决于名义BaF2掺杂量x.在实验范围内,掺杂量越大,转变温度越高,当x=0.2时,Tc达到50K.磁电阻测量表明:高掺杂量样品(例如x=0.2)具有较高的上临界场(Hc2)和不可逆场(Hirr),其剩余电阻率(RRR)也较大.交流磁化率和磁化临界电流密度研究表明,低磁场下磁通耗散在10-2～10-4秒时间窗口变化并不明显,而高应用磁场下其磁通钉扎力密度(Fp)对温度依赖性强,中高温区下降到小于10MN/m3.表明:高磁热状态下,当前多晶体样品的磁通钉扎性能有待提高.Binary doping effect is studied for the Fe-based superconductors of Nd1-xBaxFeAsO1-2xF2x（x= 0. 05, 0. 1, 0. 15, 0. 2） synthesized by two step solid state reaction. Temperature dependences of electric resistivity reveal that the superconductivity for the studied system emerges at x = 0. 1, and enhances together with irreversibility fields （Hirr） and upper critical fields （He2） as the doping content x increases further. In case of x= 0. 2, the superconducting critical temperature （To） reaches as high as 50K, the ac susceptibility and critical current density indicate the similar flux dissipation behavior within the time windows of 10 ^-2 -10^-4, while the strong temperature dependence of flux pinning but low pinning force density （Fp）, decreasing to several MN/ma at middle to high temperature region. This suggests the current polycrystalline samples should be improved in high magneto-thermal state.

关 键 词：铁基超导 双掺杂 临界电流密度 

分 类 号：O511.4[理学—低温物理]