1Center for Superconducting Physics and Materials, National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China 2Center for High Pressure Science and Technology Advanced Research (HPSTAR), Beijing 100094, China
Abstract：We successfully grow a new superconductor GaBa$_{2}$Ca$_{3}$Cu$_{4}$O$_{11+ \delta}$ (Ga-1234) with a transition temperature of 113 K, using the Walker-type high-pressure synthesis apparatus. X-ray diffraction measurements on the powderized samples show a mixture of the Ga-1234 phase and the Ca$_{0.85}$CuO$_{2}$ phase, and the former is dominant. Under the scanning electron microscope, plate-like crystals of the Ga-based 1234 phase with shiny surfaces can be seen. The obtained local chemical compositions revealed by energy dispersion x-ray spectroscopy are very close to the stoichiometric values. On some sub-millimeter crystal-like samples of the 1234 phase, we obtain a full Meissner shielding volume. From the temperature-dependent magnetizations, we determine the irreversibility fields and find that the system exhibits a highly anisotropic behavior.
2023, Vol. 40 
