Intra- and intersite electronic excitations in multiferroicTbMnO3probed by resonant inelastic x-ray scattering

Abstract

Mn 3d valence states and elementary electronic excitations in single-crystalline TbMnO 3 were probed with resonant inelastic x-ray scattering ͑RIXS͒ ͑or resonant x-ray emission spectroscopy, RXES͒, polarized x-ray absorption spectra and ab initio electron-structure calculations. Polarized Mn K-edge x-ray absorption spectra of TbMnO 3 crystals exhibit a significant anisotropy along three crystallographic directions, particularly for the white-line region. The 1s3p-RXES spectra obtained at the Mn K edge reveal that the quadrupolar Raman regime is restricted predominantly to below the pre-edge peak whereas the fluorescence regime starts from the first pre-edge peak of 1s → 3d transitions, indicating a relatively delocalized character of unoccupied Mn 3d states. The additional K␤ emission profile at energy loss ϳ62 eV is attributed to the off-site dipole Mn 1s-MnЈ 3d and/or Mn 1s-Tb 5d transitions, originating from hybridization between Mn 4p states and neighboring MnЈ 3d / Tb 5d states. The off-site dipole transition makes a considerable contribution to the pre-edge region of Mn K-edge spectrum. Three prominent RIXS features at ϳ2.9, 7, and 11 eV were observed. Based on GGA+ U calculations, the 7 eV region corresponds to transitions from O 2p states to unoccupied minority Mn 3d states, whereas the 11 eV band is ascribed to transitions from the O 2p band to the empty Tb 5d band. The broad 2.9 eV band is attributed to the coexistence of on-site Mn 3d-Mn 3d and off-site Mn 3d-MnЈ 3d transitions.

Experimental and ab initio investigations of the x-ray absorption near edge structure of orthorhombic LuMnO3

“…The white lines B in both spectra arise from the 1s to 4p Mn dipole transitions, and the shoulders A can be attributed to the hybridization between Mn 4p and Re 5s orbitals. 23 However, comparing the positions of the white lines B and the features C, respectively, shifts of 1 and 3 eV toward higher energies are observed for o-LMO, which are related to the larger distortion of MnO 6 induced by the decrease in the size of the Re-ion. Similar spectral shifts resulting from a smaller rare earth element were also observed in the Mn K-edge measurements of ferroelectromagnetic hexagonal ScMnO 3 compared to hexagonal YMnO 3 .…”

“…Similar edge shifts were also observed in other Mn compounds. 22 Although having the same edge positions, orthorhombic and hexagonal LuMnO 3 show very different XANES spectra, especially in the pre-edge regions due to their different manganese coordination geometries of MnO 6 octahedra and MnO 5 trigonal bipyramids, 23 as well as the corresponding crystal field splitting and orbital hybridizations. 24 A superposition of the PFY Mn K-edge spectra of both bulk o-TMO and o-LMO samples is shown in Fig.…”

“…Thus, the o-LMO pre-edge features can also be considered to be a mixture of the quadrupole 1s-3d transition and the off-site dipole transition as a result of hybridization between 4p and 3d states of neighboring Mn atoms like in o-TMO. 23 However, due to the larger MnO 6 distortion in o-LMO, the orbital hybridization between neighboring Mn atoms could be correspondingly altered and thus result in the onset of the third peak in the pre-edge region. To investigate the structural origin of the o-LMO pre-edge, XANES measurements with different polarizations directions were performed on the 60 nm o-LMO film.…”

First-Principle Construction of U(1) Symmetric Matrix Product States

“…One kind of such systems are low-dimensional quantum magnets, such as: quasi-one-dimensional compounds based on ions of various metals [1]; spin ladders [2]; high-temperature superconductors and frustrated antiferromagnets [3]. Another kind are ultracold atomic gases: the simplest example is Bose-Einstein condensate (BEC) [4]; however, quantum models with topological order [5,6] have also been realized with cold atoms [7,8].…”

Tensor Network Approach to Phase Transitions of a Non-Abelian Topological Phase

“…-In recent years theoretical and experimental search for topological quantum phases of matter with anyonic excitations have attracted considerable attention, because non-abelian quasiparticles are necessary ingredient for topological quantum computation [1][2][3][4][5]. Since the non-abelian topological phases are characterized by fractionalized degrees of freedom [3,6], the Landau-Ginzburg-Wilson theory cannot be used to characterize these exotic phases, and their phase transition to other non-topological phases is an important open problem.…”