Growth of large single crystals of BaFe1.87Co0.13As2 using a nucleation pole

Co-doped iron arsenic single crystals of BaFe1.87Co0.13As2 with dimensions up to 20 x 10 x 2 mm3 were grown using a nucleation pole: an alumina stick served as a nucleation center during growth. The high quality of the crystals was illustrated using measured neutron rocking curves and x-ray diffraction patterns. A very sharp superconducting transition temperature of Tc∼25 K was revealed by both resistivity and susceptibility measurements. A nearly 100% shielding fraction and the bulk nature of the superconductivity for the single crystals were confirmed using magnetic susceptibility data.