Calculation of Jahn‐Teller Coupling Constants of 3d Transition metal Ions in Crystals. I. General Theory

Никифоров, А. Е.; Shashkin, S. Yu.; Krotkii, A. I.

doi:10.1002/pssb.2220970212

Cited by 16 publications

(4 citation statements)

References 5 publications

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“…Indeed, taking the values g i = −300 cm −1 (Ref. 45) and V e , a, and c like before 41 we found that for a Mn-Mn pair in the ac-plane the minimum of the total energy U z−z = H ij z−z + g i cos 3ϕ i + g j cos 3ϕ j is shifted away from ϕ i = −2π/3 and ϕ j = 2π/3 towards ϕ i = −ϕ j = 113 • . The corresponding energy coupling per one pair is −485 cm −1 , i.e.…”

Section: Resultsmentioning

confidence: 99%

ESR evidence for partial melting of the orbital order inLaMnO3below the Jahn-Teller transition

et al. 2014

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We report on high-temperature electron spin resonance studies of a detwinned LaMnO3 single crystal across the Jahn-Teller transition at TJT = 750 K. The anisotropy of the linewidth and gfactor reflects the local Jahn-Teller distortions in the orbitally ordered phase. A clear jump in the linewidth accompanies the Jahn-Teller transition at TJT = 750 K confirming that the transition is of first order. Already at T * = 550 K a significant decrease of the reduced linewidth is observed. This temperature scale is discussed with respect to the interaction of the eg-electrons of the Mn 3+ -ions and the elastic field of the cooperative distortions. Our results support a partial melting of the orbital order along the antiferromagnetically coupled b-axis at T * . The remaining two-dimensional orbital ordering within the ferromagnetically coupled ac-plane finally disappears together with the cooperative distortion at TJT. Moreover in our discussion we show that elastic strain field interactions can explain the melting of the orbital order and, thus, has to be taken into account to explain the orbital ordering in LaMnO3.

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Section: Resultsmentioning

confidence: 99%

ESR evidence for partial melting of the orbital order inLaMnO3below the Jahn-Teller transition

et al. 2014

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“…7 X ⌫ are symmetric orbital operators, acting on the 3d-t 2g triplet, and V ␣ ͑␣ = e , t , a , b , c͒ and V ␣ R ͑␣ = e , t͒ are electron-lattice coupling constants. 26,27 The expressions in the first two square brackets, which are H lin and H QQ , represent interactions of the Ti 3+ 3d-t 2g electron with the linear and quadratic symmetrized shifts of the oxygen octahedron correspondingly, and H R ͑the third expression͒ is responsible for this electron and a cube of R ions shifts coupling.…”

Section: Orbital Ground Statementioning

confidence: 99%

“…26,27 For each constant V ␣ any of the above-mentioned Qs with appropriate ⌫ may be used. For example, V e is equal to ‫͗ץ‬H vib ͘ / ‫ץ‬Q and also to ‫͗ץ‬H vib ͘ / ‫ץ‬Q ⑀ .…”

Section: Orbital Ground Statementioning

confidence: 99%

Theory of magnetic resonance as an orbital state probe

Mozhegorov¹,

Larin²,

Никифоров³

et al. 2009

Phys. Rev. B

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It is demonstrated that magnetic resonance in a magnetically ordered state is a sensitive indirect method for the investigation of the orbital ground state. This idea is illustrated for two perovskite titanates: LaTiO 3 and YTiO 3 . In contrast to the spin-wave energy spectra, antiferromagnetic resonance spectra in an external magnetic field reveal clear dependence on the orbital state and it can distinguish the state with strong orbital fluctuations from the static orbital order. Our theoretical analysis is based on the model, which explicitly takes into consideration the strong correlation among lattice, orbital, and magnetic degrees of freedom.

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“…where the index k numbers all of the copper ions in the unit cell and the symmetrized coordinates Q θ , Q characterize the e g distortion of the oxide octahedra around the copper ions (for more details, see [10]). Evaluation of the linear Jahn-Teller coupling constant V e for the CuO 6 cluster with the distance R(Cu-O) = 0.21 nm (the average Cu-O distance in La 2 CuO 4 ) with the aid of the method of [14] gives V e = −2.5 nN.…”

Section: The Modelmentioning

confidence: 99%

Elastic properties of La₂CuO₄under pressure

Никифоров¹,

Shashkin²,

Zaharov³

2000

J. Phys.: Condens. Matter

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Within the framework of the pair potential approximation and the shell model including the Jahn-Teller contribution to the crystal energy we have studied the elastic properties of La 2 CuO 4 . The strong anisotropic correlation between the lattice deformations e xx and e zz and the internal displacements of the accompanying sublattices within the La 2 O 2 layers are shown to be responsible for the giant anisotropy of the elastic moduli in the xz-plane. We have predicted the softening of several elastic moduli in the orthorhombic phase region near the pressure-induced structural phase transition. But we have not observed the softening of c 11 , c 12 , and c 66 in the tetragonal phase region that was measured near the temperature-induced structural phase transition.

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Calculation of Jahn‐Teller Coupling Constants of 3d Transition metal Ions in Crystals. I. General Theory

Abstract: A method is proposed for the calculation of the Jahn-Teller coupling constants for orbitally degenerated states of ions in crystals based on the applicat,ion of perturbation theory in adiabatic potential matrix caIcuIation. The cluster approximation and LCAO-MO scheme are used.

Cited by 16 publications

References 5 publications

ESR evidence for partial melting of the orbital order inLaMnO3below the Jahn-Teller transition

ESR evidence for partial melting of the orbital order inLaMnO3below the Jahn-Teller transition

Theory of magnetic resonance as an orbital state probe

Elastic properties of La₂CuO₄under pressure

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Calculation of Jahn‐Teller Coupling Constants of 3d Transition metal Ions in Crystals. I. General Theory

Abstract: A method is proposed for the calculation of the Jahn-Teller coupling constants for orbitally degenerated states of ions in crystals based on the applicat,ion of perturbation theory in adiabatic potential matrix caIcuIation. The cluster approximation and LCAO-MO scheme are used.

Cited by 16 publications

References 5 publications

ESR evidence for partial melting of the orbital order inLaMnO3below the Jahn-Teller transition

ESR evidence for partial melting of the orbital order inLaMnO3below the Jahn-Teller transition

Theory of magnetic resonance as an orbital state probe

Elastic properties of La2CuO4under pressure

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Product

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About

Elastic properties of La₂CuO₄under pressure