PC-9-3
Single crystal growth of iron-based superconductors with thick perovskite type blocking layers
11:15-11:30 30/11/2023
*Hiraku Ogino, Yudai Yatsu, Shigeyuki Ishida, Yoichi Higashi, Naomichi Sakai, Rayko Simura
National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
Shibaura Institute of Technology, Koto, Tokyo 135-8548, Japan
Tohoku University, Sendai, Miyagi 980-8577, Japan
One of the important features of iron-based superconductors is the great variety of block layer structures. Among them, compounds with perovskite-type block layers have thick block layers, and interesting properties such as very large anisotropy, and interlayer Josephson junctions[1] are reported. However, only Sr2VFeAsO3 has been reported to grow single crystals of about 300mm in this system[2]. On the other hand, various compounds exist in this system, such as Ca n+1(Sc,Ti)n Fe2As2O n+3[3], which has a thicker block layer and a higher superconducting transition temperature(T c) more than 40 K. In this presentation, we report on the successful fabrication and structural analysis of single crystals of Ca n+1(Sc,Ti)n Fe2As2O n+3.
The samples were prepared by the self-flux method using FeAs. The starting composition, flux and raw material ratio were adjusted based on the composition of Ca5(Sc,Ti)4Fe2As2O11:FeAs = 1:4. The phase identification and structural analysis by X-ray diffraction, observation and compositional analysis by scanning electron microscope (SEM-EDS), magnetization measurement by magnetic property measurement system (MPMS), and electrical resistance measurement by four-terminal method were evaluated.
We succeeded in synthesizing single crystals of Ca5(Sc,Ti)4Fe2As2O11 by optimization of various conditions. In some cases Ca5(Sc,Ti)4Fe2As2O11were exclusively formed, and single crystals of several hundred microns square were successfully isolated as shown in Fig. 1. The crystal structure of the crystal was analyzed by single crystal structure analysis. The basic structure is stacking of FeAs and four perovskite layers as previously reported, and the (Sc,Ti) sites are Ti-rich and the oxygen sites inside the oxide layer are split sites to suppress the atomic displacement parameter. Details of the physical properties will be reported in the presentation.
[1] P.J.W. Moll et al., Nat. Phys. 10 (2014) 644.
[2] K.Katagiri, T.Sasagawa: Physica C 484 (2013) 16.
[3]H. Ogino et al., Appl. Phys. Let. 97 (2010) 072506.
