Single-crystal growth and physical properties of the antiferromagnetic double perovskite Ba 2 CoMoO 6

This work presents a comprehensive investigation of the structural, magnetic, and electronic properties of the double perovskite Ba 2 CoMo O 6 (BCMO). Single crystals were grown via floating-zone and Czochralski growth techniques and characterized using a set of complementary methods. X-ray diffraction analysis confirmed that BCMO crystallizes in a face-centered-cubic (fcc) structure with space group . Magnetic susceptibility measurements exhibit antiferromagnetic ordering below T N = 20.1 ( 1 ) K. A spin-flop transition is observed at 26.5 kOe. Heat capacity measurements and entropy analysis are consistent with a J eff = 1 / 2 ground state for C o 2 + ions. X-ray absorption spectroscopy provided insight into the local electronic structure, revealing the spin-orbit and crystal-field effects. The cluster-model analysis yields a g factor of 4.36, consistent with a spin-orbit-entangled ground state. Surface photovoltage spectroscopy demonstrates a strong near-surface optical response with an onset near 1.5 eV and a pronounced feature at 2.65 eV, consistent with visible-range Co-O-Mo transitions in line with related Ba-based double perovskites, highlighting its potential for spintronic and energy-conversion applications.