Low temperature specific heat of 12442-type KCa2Fe4As4F2 single crystals

作者：Teng Wang,JiaNan Chu,JiaXin Feng,LingLing Wang,XuGuang Xu,Wei Li,HaiHu Wen,XiaoSong Liu,Gang Mu

摘要：Low-temperature specific heat(SH)is measured for the 12442-type KCa2Fe4As4F2 single crystal under different magnetic fields.A clear SH jump with the height of?C/T|Tc=130 mJ mol-1 K-2 is observed at the superconducting transition temperature Tc.It is found that the electronic SH coefficient?γ(H)quickly increases when the field is in the low-field region below 3T and then considerably slows down the increase with a further increase in the field,which indicates a rather strong anisotropy or multi-gap feature with a small minimum in the superconducting gap(s).The temperature-dependent SH data indicate the presence of the T2 term,which supplies further information and supports the picture with a line-nodal gap structure.Moreover,the onset point of the SH transition remains almost unchanged under the field as high as 9 T,which is similar to that observed in cuprates,and places this system in the middle between the BCS limit and the Bose-Einstein condensation.

发文机构：State Key Laboratory of Functional Materials for Informatics CAS Center for Excellence in Superconducting Electronics（CENSE） School of Physical Science and Technology University of Chinese Academy of Sciences State Key Laboratory of Surface Physics and Department of Physics Collaborative Innovation Center of Advanced Microstructures Center for Superconducting Physics and Materials

关键词：specificheatgapstructureKCa2Fe4As4F2

分类号： O469[理学—凝聚态物理]