Sr_(1-x)Ln_xFBiS_2(Ln=La,Ce)体系的超导电性

Superconductivity in Sr_(1-x)Ln_xFBiS_2(Ln=La,Ce)System

在新发现的SrFBiS_2体系掺杂稀土元素镧和铈,利用固相反应法成功合成出Sr_(0.5)Ln_(0.5)FBiS_2(Ln=La,Ce)多晶样品.通过X射线衍射、电阻和磁化强度测量,发现母体样品SrFBiS_2是一个半导体,通过La或者Ce掺杂后,Sr_(0.5)Ln_(0.5)FBiS_2(Ln=La,Ce)在2.8K展现出大块超导电性.同时,研究发现Sr_(0.5)Ce_(0.5)FBiS_2先在7.5K形成铁磁序,然后在2.8K进入超导态,是一个铁磁超导体.这些结果对研究BiS_2基超导机制以及铁磁与超导共存的内在联系具有重要意义.

Through solid state reaction method, the Sr0.5 Ln0.5 FBiS2 （Ln = La, Ce） polycrystalline samples are synthesized using rare earth elements Lanthanum and Cerium doping into Sr site. The X-ray diffraction measurement, electrical transport and magnetic susceptibility measurements show that the parent sample SrFBiS2 is a semiconductor. La or Ce doping can induce superconductivity at about 2.8 K＋ in Sr0. 5 Ln0. 5 FBiS2 （Ln= La, Ce）. Meanwhile, Sr0. 5 Ce0.5 FBiS2 not only orders ferromagnetically below 7. 5K, but exhibits superconductivity at 2. 8K, implying the coexistence of superconductivity and ferromagnetism. Those findings play an important role in studying the superconducting mechanism in the BiS2-based superconductors as well as the relationship between superconductivity and ferromagnetism.