Optical Spectroscopy in CoO: Phonons, Electric, and Magnetic Excitations

Abstract

The reflectivity of single-crystalline CoO has been studied by optical spectroscopy for wave numbers ranging from 100 to 28,000\wn and for temperatures 8 $<T<$ 325 K\@. A splitting of the cubic IR-active phonon mode on passing the antiferromagnetic phase transition at $T_N$ = 289 K has been observed. At low temperatures the splitting amounts to 15.0\wn. In addition, we studied the splitting of the cubic crystal field ground state of the Co${}^{2+}$ ions due to spin-orbit coupling, a tetragonal crystal field, and exchange interaction. Below $T_N$, magnetic dipole transitions between the exchange-split levels are identified and the energy-level scheme can be well described with a spin-orbit coupling $λ= 151.1\wn$, an exchange constant $J = 17.5\wn$, and a tetragonal crystal-field parameter $D = -47.8\wn$. Already in the paramagnetic state electric quadrupole transitions between the spin-orbit split level have been observed. At high frequencies, two electronic levels of the crystal-field-split $d$-manifold were identified at 8,000 and 18,500\wn.

12 pages, 8 figures, 2 tables

References in corpus (9)

• Spin-phonon coupling in antiferromagnetic chromium spinels
• Spin-driven Phonon Splitting in Bond-frustrated ZnCr2S4
• Non-resonant inelastic x-ray scattering involving excitonic excitations
• Spin Frustration and Magnetic Exchange in Cobalt Aluminum Oxide Spinels
• Spin-phonon coupling in ZnCr2Se4
• Optical evidence for symmetry changes above the Neel temperature in KCuF3
• Spin phonon coupling in frustrated magnet CdCr${}_2$O${}_4$
• Magnetic-order induced phonon splitting in MnO from far-infrared spectroscopy
• Orbital and Spin Excitations in Cobalt Oxide

Cited by in corpus (7)

• Long range antiferromagnetic order in a rocksalt high entropy oxide
• Hubbard-corrected density functional perturbation theory with ultrasoft pseudopotentials
• Magnetic order and dynamics of the charge-ordered antiferromagnet La1.5Sr0.5CoO4
• Magnetic spectrum of the two-dimensional antiferromagnet La2CoO4 studied by inelastic neutron scattering
• Lattice dynamics and spontaneous magnetodielectric effect in ilmenite CoTiO${}_3$
• Spin-orbiton and quantum criticality in FeSc2S4
• Transverse acoustic phonon anomalies at intermediate wavevectors in MgV${}_2$O${}_4$