Magnetization and specific heat of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">LaTiO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

Fritsch, V.; Erëmin, M. V.; Nidda, H.-A. Krug von; Lichtenberg, F.; Wehn, R.; Loidl, A.

doi:10.1103/physrevb.65.212405

Cited by 37 publications

(40 citation statements)

References 21 publications

(22 reference statements)

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“…The puzzling magnetic properties of LaTiO 3 led Khaliullin and Maekawa to suggest a novel theoretical description for RETiO 3 based on the idea of an orbital liquid. They were able to explain many of the magnetic characteristics of LaTiO 3 [3], but the presumed orbital fluctuations have not been observed [8]. Therefore, magnetism in LaTiO 3 still remains an open issue.…”

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confidence: 99%

Crystal and magnetic structure ofLaTiO3:Evidence for nondegeneratet2g
Cwik
¹
,
Lorenz
²
,
Baier
³

et al. 2003
Phys. Rev. B
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The crystal and magnetic structure of LaTiO3 has been studied by x-ray and neutron diffraction techniques using nearly stoichiometric samples. We find a strong structural anomaly near the antiferromagnetic ordering, TN =146 K. In addition, the octahedra in LaTiO3 exhibit an intrinsic distortion which implies a splitting of the t2g-levels. Our results indicate that LaTiO3 should be considered as a Jahn-Teller system where the structural distortion and the resulting level splitting are enhanced by the magnetic ordering.LaTiO 3 has been studied already in the seventies and was thought to be a text book example of a Mottinsulator with antiferromagnetic order [1]. Ti is in its three-valent state with a single electron in the t 2g -orbitals of the 3d-shell. The titanate is hence an electron analog to the cuprates with a single hole in the 3d-shell. However, the t 2g -orbitals in the LaTiO 3 are less Jahn-Teller active and, therefore, the orbital moment may not be fully quenched in the titanate. The physics of the orbital degree of freedom has recently reattracted attention to this material [2,3].The ordered moment in LaTiO 3 amounts to 0.46 µ B which is much smaller than the value of 1µ B expected for a single electron with quenched orbital moment [4]. Quantum fluctuations can explain only about 15% reduction in the 3D-case. A straight-forward explanation could be given in terms of spin-orbit coupling, as an unquenched orbital moment would align antiparallel to the spin-moment in the titanate. However, in a recent neutron scattering experiment the magnon spin gap was observed at 3.3 meV, and it was argued that the strong interaction of an orbital moment with the crystal lattice implies a much larger value for the spin gap [2]. An orbital contribution to the ordered moment in LaTiO 3 was hence excluded. On the basis of standard theories, however, even the G-type antiferromagnetic ordering in LaTiO 3 may not be explained without a spinorbit coupling. Instead one expects ferromagnetism [5,6] related with the orbital degeneracy. Under the assumption of a specific structural distortion, Moshizuki and Imada recently presented a successful model for the antiferromagnetic order in LaTiO 3 [7]. However, there is no experimental evidence for such a distortion. The puzzling magnetic properties of LaTiO 3 led Khaliullin and Maekawa to suggest a novel theoretical description for RETiO 3 based on the idea of an orbital liquid. They were able to explain many of the magnetic characteristics of LaTiO 3 [3], but the presumed orbital fluctuations have not been observed [8]. Therefore, magnetism in LaTiO 3 still remains an open issue.We have reanalyzed the crystal and magnetic structure of LaTiO 3 by x-ray and by neutron diffraction samples with almost perfect stoichiometry. First, we find a clear structural anomaly at the Néel-ordering and, second, the shape of the octahedra in this compound is not ideal but distorted. From these observations we conclude that LaTiO 3 has to be considered as a soft Jahn-Teller system thereby explaining m...

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confidence: 99%

Crystal and magnetic structure ofLaTiO3:Evidence for nondegeneratet2g
Cwik
¹
,
Lorenz
²
,
Baier
³

et al. 2003
Phys. Rev. B
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32
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1
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“…In an earlier publication 23 it was mentioned that the anisotropy observed in the paramagnetic regime requires to include the spin-orbit coupling into the crystal-field calculation.…”

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Anisotropy of the paramagnetic susceptibility in LaTiO3: The electron-distribution picture in the ground state

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The energy-level scheme and wave functions of the titanium ions in LaTiO3 are calculated using crystal-field theory and spin-orbit coupling. The theoretically derived temperature dependence and anisotropy of the magnetic susceptibility agree well with experimental data obtained in an untwinned single crystal. The refined fitting procedure reveals an almost isotropic molecular field and a temperature dependence of the van Vleck susceptibility. The charge distribution of the 3d-electron on the Ti positions and the principle values of the quadrupole moments are derived and agree with NMR data and recent measurements of orbital momentum l and crystal-field splitting. The low value of the ordered moment in the antiferromagnetic phase is discussed.

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“…13 Furthermore, an orbital contribution to the specific heat, which is predicted by the orbitalliquid model, has not been found in experiment. 14 Hence from the recent experiments it must be concluded that the orbital-liquid model is inappropriate for LaTiO 3 . Moreover, it has been proven, by exact symmetry arguments, that due to a hidden symmetry the superexchange Hamiltonian used in Ref.…”

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Magnetic structure of the Jahn-Teller systemLaTiO3

et al. 2005

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We investigate the effect of the experimentally observed Jahn-Teller distortion of the oxygen octahedra in LaTiO 3 on the magnetic exchange. We present a localized model for the effective hopping between nearestneighbor Ti ions and the intrasite Coulomb interactions, based on a nondegenerate orbital ground state due to the static crystal field. The latter corresponds to an orbital order which has recently been confirmed experimentally. Using perturbation theory we calculate, in addition to the Heisenberg coupling, antisymmetric (Dzyaloshinskii-Moriya) and symmetric anisotropy terms of the superexchange spin Hamiltonian, which are caused by the spin-orbit interaction. Employing this spin Hamiltonian, we deduce that at low temperatures the spins have predominantly a G-type antiferromagnetic ordering along the crystallographic a axis, accompanied by a weak ferromagnetic moment along the c axis and by a weak A-type antiferromagnetic moment along the b axis. The first two components are found to be in good agreement with experiment. Disciplines PhysicsThis journal article is available at ScholarlyCommons: http://repository.upenn.edu/physics_papers/333 We investigate the effect of the experimentally observed Jahn-Teller distortion of the oxygen octahedra in LaTiO 3 on the magnetic exchange. We present a localized model for the effective hopping between nearestneighbor Ti ions and the intrasite Coulomb interactions, based on a nondegenerate orbital ground state due to the static crystal field. The latter corresponds to an orbital order which has recently been confirmed experimentally. Using perturbation theory we calculate, in addition to the Heisenberg coupling, antisymmetric ͑Dzyaloshinskii-Moriya͒ and symmetric anisotropy terms of the superexchange spin Hamiltonian, which are caused by the spin-orbit interaction. Employing this spin Hamiltonian, we deduce that at low temperatures the spins have predominantly a G-type antiferromagnetic ordering along the crystallographic a axis, accompanied by a weak ferromagnetic moment along the c axis and by a weak A-type antiferromagnetic moment along the b axis. The first two components are found to be in good agreement with experiment.

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Magnetization and specific heat ofLaTiO3

Cited by 37 publications

References 21 publications

Crystal and magnetic structure ofLaTiO3:Evidence for nondegeneratet2g
Cwik
¹
,
Lorenz
²
,
Baier
³

et al. 2003
Phys. Rev. B
Self Cite
206
32
222
1
View full text Add to dashboard Cite

Crystal and magnetic structure ofLaTiO3:Evidence for nondegeneratet2g
Cwik
¹
,
Lorenz
²
,
Baier
³

et al. 2003
Phys. Rev. B
Self Cite
206
32
222
1
View full text Add to dashboard Cite

Anisotropy of the paramagnetic susceptibility in LaTiO3: The electron-distribution picture in the ground state

Magnetic structure of the Jahn-Teller systemLaTiO3

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Magnetization and specific heat ofLaTiO3

Cited by 37 publications

References 21 publications

Crystal and magnetic structure ofLaTiO3:Evidence for nondegeneratet2gCwik1, Lorenz2, Baier3 et al. 2003Phys. Rev. BSelf Cite206322221View full textAdd to dashboardCite

Crystal and magnetic structure ofLaTiO3:Evidence for nondegeneratet2gCwik1, Lorenz2, Baier3 et al. 2003Phys. Rev. BSelf Cite206322221View full textAdd to dashboardCite

Anisotropy of the paramagnetic susceptibility in LaTiO3: The electron-distribution picture in the ground state

Magnetic structure of the Jahn-Teller systemLaTiO3

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Product

Resources

About

Crystal and magnetic structure ofLaTiO3:Evidence for nondegeneratet2g
Cwik
¹
,
Lorenz
²
,
Baier
³

et al. 2003
Phys. Rev. B
Self Cite
206
32
222
1
View full text Add to dashboard Cite

Crystal and magnetic structure ofLaTiO3:Evidence for nondegeneratet2g
Cwik
¹
,
Lorenz
²
,
Baier
³

et al. 2003
Phys. Rev. B
Self Cite
206
32
222
1
View full text Add to dashboard Cite