Luminescence of Mn (IV) complexes

Paulusz, A. G.; Burrus, H. L.

doi:10.1016/0009-2614(72)85097-8

Cited by 15 publications

(4 citation statements)

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Section: The Hole Mno 8− 6 Center In Doped Manganites: Conventional T...supporting

confidence: 92%

“…The authors observed two rather narrow magneto-optical features in the range 2.6 − 3.1 eV, related to the d − d transitions 4 A 2g − 4 T 2g and 4 A 2g − 4 T 1g , respectively, and two rather wide features near 3.7 − 3.9 eV and ≥ 4.3 eV, associated with CT transitions. This assignment agrees with data by Paulusz and Burrus [18], and Jung et al for center is a half-filled configuration t 3 2g e 2 g and the orbital singlet term 6 A 1g , respectively. In the framework of crystal field model this term originates from the (3d 56 S) term of free Mn 2+ ion.…”

Section: The Hole Mno 8− 6 Center In Doped Manganites: Conventional Tsupporting

confidence: 91%

“…The classification scheme for the CT transitions in octahedral MnO 8− 6 centers is similar to that of MnO 9− 6 centers, described above. As for manganite LaMnO 3 [18], the minimal energy of 5 the allowed CT transitions is estimated to be ∆ CT ∼ 4.0 eV. The luminescence measurements in [19] give the energies 2.6 eV and 3.1 eV for 4 A 2g − 4 T 2g and 4 A 2g − 4 T 1g transitions, respectively.…”

Section: The Hole Mno 8− 6 Center In Doped Manganites: Conventional Tmentioning

confidence: 99%

“…centers is similar to that of MnO 9− 6 centers, described above. As for manganite LaMnO 3[18], the minimal energy of…”

mentioning

confidence: 99%

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Doped manganites beyond conventional double-exchange model

Moskvin

Avvakumov

2002

Physica B: Condensed Matter

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The problem of adequate electronic model for doped manganites like La 1−x Sr x MnO 3 remains controversial. There are many thermodynamic and local microscopic quantities that cannot be explained by the conventional double-exchange model with dominantly Mn3d location of doped holes. In such a situation we argue a necessity to discuss all possible candidate states with different valent structure of manganese and oxygen atoms, as well as different valent states of octahedral MnO 6 centers.In frames of rather conventional quantum-chemical approach, crystal field and the ligand field model we address different types of MnO 6 centers, different types of d − d, and charge transfer transitions. We draw special attention to the so-called charge transfer states related to strong intracenter charge fluctuations. As we conjecture, namely these could become active valent states for doped manganites. We discuss some electric and magnetic properties of the electron MnO 10− 6 , and hole MnO 8− 6 centers with unconventional 6 A 1g − 6 T 1u and 4 A 2g − 4 T 2u valent manifolds, respectively. We propose two idealized theoretical models for hole system in doped manganites. The first one implies an overall oxygen localization for the doped holes occupying the non-bonding O2p orbitals. The second assumes a doping induced formation of the electron-hole Bose liquid, or a system of the electron MnO 10− 6 , and hole MnO 8− 6 centers. In a sense, this scenario resembles a well-known disproportionation reaction. In both cases one might expect non-trivial magnetic behavior with strong ferromagnetic fluctuations due to anomalously strong ferromagnetic coupling of non-bonding O2p holes with Mn3d electrons. 1 model [1]. The model is a generalization of the well-known double exchange model [2,3] and implies a predominantly Mn3d character of valent states both for parent and hole-doped system. Indeed, according to the conventional band theory calculations [4,5] the conduction band of LaMnO 3 is derived mainly from Mne g symmetry d-orbitals and is well separated from other bands. So, the low energy (hω ≤ 4 eV ) physics of these materials is believed to be governed by Mn e g electrons, which are coupled by a strong Hund's coupling, J H to Mn t 2g symmetry "core spins" and also interact which each other and with lattice distortions [4]. This model has been developed, in particular, with aim to relevantly describe the low frequency conductivity data [4]. An appropriate effective Hamiltonian could be represented as a sum of several termŝwhere λ is a vibronic constant,d † iν (d iν ) is a two-component (a, b) creation (annihilation) operator, σ x,z Pauli matrices, Q 2,3 are oxygen displacement modes for octahedral MnO 6 centers. The Hund coupling is written as followsĤ

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Section: The Hole Mno 8− 6 Center In Doped Manganites: Conventional T...supporting

confidence: 92%

Section: The Hole Mno 8− 6 Center In Doped Manganites: Conventional Tsupporting

confidence: 91%

Section: The Hole Mno 8− 6 Center In Doped Manganites: Conventional Tmentioning

confidence: 99%

“…centers is similar to that of MnO 9− 6 centers, described above. As for manganite LaMnO 3[18], the minimal energy of…”

mentioning

confidence: 99%

See 2 more Smart Citations