Tunnel effects in polyatomic systems with electronic degeneracy and pseudodegeneracy

Берсукер, И. Б.; Vekhter, B. G.; Ogurtsov, I. Ya.

doi:10.3367/ufnr.0116.197508d.0605

Cited by 42 publications

(18 citation statements)

References 14 publications

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“…3(e,f)] are closely related to the orbital excitations of quantum rotor states in the "Mexican hat" [see Fig. 1(c)] [10,34,35]. The effect of anharmonicity barriers on the lowest state of the system, which is supposed to derive entirely from the lowest "Mexican hat" energy surface, is considered by O'Brien [10].…”

Section: Discussionmentioning

confidence: 99%

Optical evidence of quantum rotor orbital excitations in orthorhombic manganites

Kovaleva

Кugel

Potůček

et al. 2016

J. Exp. Theor. Phys.

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Abstract. In magnetic compounds with Jahn-Teller (JT) ions (such as Mn 3+ or Cu 2+ ), the ordering of the electron or hole orbitals is associated with cooperative lattice distortions. There the role of JT effect, although widely recognised, is still elusive in the ground state properties. We suggest that, in these materials, there exist elementary excitations whose energy spectrum is described in terms of the total angular momentum eigenstates and is quantised as in quantum rotors found in JT centers. We observed features originating from these excitations in the optical spectra of a model compound LaMnO 3 using ellipsometry technique. They appear clearly as narrow sidebands accompanying the electron transition between the JT split orbitals on neighbouring Mn 3+ ions, strongly influenced by anisotropic spin correlations. We present these results together with new experimental data on photoluminescence and its kinetics found in LaMnO 3 , which lend additional support to the ellipsometry implying the existence of the quantum rotor orbital excitations. We note that the discovered elementary excitations of quantum rotors may play an important role in many unusual properties observed in these materials upon doping, such as hightemperature superconductivity and colossal magnetoresistance.

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Section: Discussionmentioning

confidence: 99%

Optical evidence of quantum rotor orbital excitations in orthorhombic manganites

Kovaleva

Кugel

Potůček

et al. 2016

J. Exp. Theor. Phys.

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“…The theoretical background of all these effects in atomic systems emerges from the first-principles as a delicate addition to the coupling between the electronic states and nuclear displacements, which occurs beyond the adiabatic approximation (vibronic coupling). The theory of the JTE and PJTE with many of their manifestations in molecular and solid state properties are rather well studied and continues developing. − Less attention has been paid so far to the PJTE, especially to its use as a tool in the study of the structure and properties of polyatomic syst...…”

Section: Introduction Improved Definition Of Polyatomic Space Configu...mentioning

confidence: 99%

Jahn–Teller and Pseudo-Jahn–Teller Effects: From Particular Features to General Tools in Exploring Molecular and Solid State Properties

Берсукер

2020

Chem. Rev.

103

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“…Surprisingly, as we have discovered during our study, aside from the oxygen-phonon density-of-states feature, there is an additional component to the multi-order scattering, which exhibits a different behaviour. We consider that this behaviour may arise from an admixture of the electronic component in the case of a weak vibronic interaction, when the barriers between the minima are less than the characteristic vibrational frequency, and a special coupling between low-frequency electronic motions and vibrational modes takes place [27,37]. We suggest that the superexchange interaction may be crucial in driving the system of e g electrons to the regime of the dynamic JT effect, with affordable barriers for the tunneling between the potential energy minima.…”

Section: Introductionmentioning

confidence: 99%

Anomalous multi-order Raman scattering in LaMnO₃: a signature of quantum lattice effects in a Jahn–Teller crystal

Kovaleva

Kusmartseva

Кugel

et al. 2013

J. Phys.: Condens. Matter

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The multi-order Raman scattering is studied up to fourth order for a detwinned LaMnO3 crystal. Based on a comprehensive data analysis of the polarization-dependent Raman spectra, we show that the anomalous features in the multi-order scattering could be the sidebands on the low-energy mode at about 25 cm(-1). We suggest that this low-energy mode stems from the tunneling transition between the potential energy minima arising near the Jahn-Teller Mn(3+) ion due to the lattice anharmonicity and that the multi-order scattering is activated by this low-energy electronic motion. The sidebands are dominated by the oxygen contribution to the phonon density-of-states, however, there is an admixture of an additional component, which may arise from coupling between the low-energy electronic motion and the vibrational modes.

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Tunnel effects in polyatomic systems with electronic degeneracy and pseudodegeneracy

Cited by 42 publications

References 14 publications

Optical evidence of quantum rotor orbital excitations in orthorhombic manganites

Optical evidence of quantum rotor orbital excitations in orthorhombic manganites

Jahn–Teller and Pseudo-Jahn–Teller Effects: From Particular Features to General Tools in Exploring Molecular and Solid State Properties

Anomalous multi-order Raman scattering in LaMnO₃: a signature of quantum lattice effects in a Jahn–Teller crystal

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Tunnel effects in polyatomic systems with electronic degeneracy and pseudodegeneracy

Cited by 42 publications

References 14 publications

Optical evidence of quantum rotor orbital excitations in orthorhombic manganites

Optical evidence of quantum rotor orbital excitations in orthorhombic manganites

Jahn–Teller and Pseudo-Jahn–Teller Effects: From Particular Features to General Tools in Exploring Molecular and Solid State Properties

Anomalous multi-order Raman scattering in LaMnO3: a signature of quantum lattice effects in a Jahn–Teller crystal

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Anomalous multi-order Raman scattering in LaMnO₃: a signature of quantum lattice effects in a Jahn–Teller crystal