X-Ray Diffraction Study on CoO

Raman spectroscopy of metals, high‐temperature superconductors and related materials under high pressure

“…11) above its Nèel temperature T N (290 K), and below T N the cubic structure becomes slightly distorted, with tetragonal distortion amounting to about 1.1% (c/a D 0.988), and an additional small rhombohedral distortion (˛DˇD D 89°58 0 ). 143 When their near environment has cubic symmetry, the magnetic Co 2C ions have a triply degenerate ground state in the paramagnetic phase of CoO. This degeneracy is lifted in the low-temperature antiferromagnetic phase by lattice distortions (which are predominantly tetragonal), and by spin-orbit interaction.…”

“…At low temperatures the space group of CoO is C 3 2h . 143 The CoO structure is displayed in Fig. 11 (note that the distortions are too small to be visible).…”

Manipulating the Magnetic Structure of Co Core/CoO Shell Nanoparticles: Implications for Controlling the Exchange Bias

“…As in bulk CoO, the magnetization of our nanoparticles has two different modulation wave vectors:q 1 and q 2 [27,29,30]. Their variations with oxidation have important consequences for the magnetic compensation of the coreshell interface.…”

“…The presence of AF peaks with both (100) and ð 1 2 1 2 1 2 Þ indices implies that two separate magnetic modulations must be present in the distorted crystal structure, as in bulk CoO [27,29,30]: q 1 ¼ 2 a ð 1 2 ; 1 2 ; 1 2 Þ and q 2 ¼ 2 a  ð1; 0; 0Þ. The q 1 modulation leads to a magnetic diffraction peak with intensity I ð1=2Þð1=2Þð1=2Þ / ðp 1;?…”

Calorimetric investigation on the paramagnetic–antiferromagnetic phase transition in CoO

“…At the Neel temperature T N D288 K, it undergoes a paramagnetic-antiferromagnetic phase transition. The magnetic ordering is coupled with a tetragonal contraction [2] along the cubic [1 0 0] directions and an additional deformation [3] along the cubic [1 1 1] directions.…”