Spin-state transition and microscopic magnetic properties of LaCoO3

Itoh, Makoto; Mori, Masami; Sugahara, M.; Yamauchi, Touru; Ueda, Yutaka

doi:10.1016/s0921-4526(96)00831-9

Cited by 11 publications

(3 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, only the oxygen hyperfine shift data are available yet. 35 Another interesting point raised by the NMR data is the absence of the field dependence of the T 1 Z Ϫ1 in the uniform phase. Numerical results for the zero-temperature spectral function perpendicular to the applied field, corresponding to the exact solution for 10 Heisenberg spins 1/2 in the magnetic field, 26 are indeed indicative of the field-independent total spectral weight near the zero energy.…”

Section: Discussionmentioning

confidence: 99%

63,65Cu NMR investigation ofCuGeO
Fagot‐Revurat
¹
,
Horvatic-acute
²
,
Berthier
³

et al. 1997
Phys. Rev. B
29
4
15
0
View full text Add to dashboard Cite

We report a Cu NMR study performed under high magnetic field on single crystals of the inorganic spin-Peierls CuGeO 3 compound, in its uniform and dimerized phases. The temperature (T) dependence of the magnetic hyperfine shift, i.e., the local static spin susceptibility, is found to scale the macroscopic susceptibility. This allows the determination of the hyperfine coupling tensor, which can be well accounted for by the on-site coupling associated with the localized electronic spin of a Cu ϩϩ ion in an approximately axially symmetric environment. The nuclear spin-lattice relaxation rate ͑T 1 Ϫ1 ͒ in the dimerized phase is found to be activated for temperature below ϳT SP /2. The magnetic-field dependence of the activation energy is in good agreement with that of the energy gap determined by neutron inelastic scattering. In the uniform phase, neither the magnitude of T 1 Ϫ1 ͑an order of magnitude smaller͒ nor its T dependence ͑approximately linear in T instead of being nearly constant͒ correspond to the theoretical predictions for a simple Sϭ1/2, one-dimensional Heisenberg antiferromagnet, unless we admit for a filtering of the antiferromagnetic fluctuations, due to a small supertransferred hyperfine coupling. As expected, we found no magnetic-field dependence of T 1 ͑Tտ1.5 T SP ͒ in the range 8.9-14.9 T.

show abstract

Section: Discussionmentioning

confidence: 99%

63,65Cu NMR investigation ofCuGeO
Fagot‐Revurat
¹
,
Horvatic-acute
²
,
Berthier
³

et al. 1997
Phys. Rev. B
29
4
15
0
View full text Add to dashboard Cite

show abstract

“…Taguchi 26 has shown from structural and susceptibility studies that Co 3+ in Nd(Cr 1−x Co x )O 3 is in the low-spin state at low temperature and transform to a mixed-spin state with increasing temperature. From temperature-dependent susceptibility and Knight-shift measurements 27 it has been pointed out that the LS-HS model is not applicable for understanding the spin-state transtion in LaCoO 3 and thus a LS-IS model is more appropriate. Heikes et al 5 considered an IS state to account for the effective moment obtained from susceptibility data below the ∼ 500 K transition in LaCoO 3 .…”

Section: Introductionmentioning

confidence: 99%

Itinerant metamagnetism and possible spin transition in LaCoO3 by temperature/hole doping

Ravindran

Fjellvåg

Kjekshus

et al. 2002

Journal of Applied Physics

112

View full text Add to dashboard Cite

The electronic structure of the perovskite La 1−x Sr x CoO 3 has been obtained as a function of Sr substitution and volume from a series of generalizedgradient-corrected, full-potential, spin-density-functional band structure calculations. The energetics of different spin configurations are estimated using the fixed-spin-moment (FSM) method. From the total energy vs spin magnetic moment curve for LaCoO 3 the ground state is found to be nonmagnetic with the Co ions in a low-spin (LS) state, a result that is consistent with the experimental observations. Somewhat higher in energy, we find an intermediate-spin (IS) state with spin moment ∼1.2 µ B /f.u. From the anomalous temperature dependent susceptibility along with the observation of an IS state we predict metamagnetism in LaCoO 3 originating from an LS-to-IS transition. The IS state is found to be metallic and the high-spin (HS) state of LaCoO 3 is predicted to be a half-metallic ferromagnet. With increasing temperature, which is simulated by a corresponding change of the lattice parameters we have observed the disappearence of the metamagnetic solution that is associated with the IS state. The FSM calculations on La 1−x Sr x CoO 3 suggest that the hole doping stabilizes the IS state and the calculated magnetic moments are in good agreement with the corresponding experimental values. Our calculations show that the HS state cannot be stabilized by temperature or hole doping since the HS state is significantly higher in energy than the LS or IS state. Hence the spin-state transition in LaCoO 3 by temperature/hole doping is from an LS to an IS spin state and the present work rules out the other possibilities reported in the literature. Typeset using REVT E X

show abstract

“…

In LnCoO 3 oxides (Ln-lanthanide) Co ions in the ground state are characterized by the low spin electronic configuration t 6 2g e 0 g . This state (LS; S = 0) gradually passes to intermediate spin one (IS; S = 1; t 5 2g e 1 g ) with temperature enhancement [1][2][3][4][5]. For example, the spin state of cobalt ions in LaCoO 3 gradually changes from LS to IS with temperature increment in the temperature range of 40-100 K.The energy difference between LS and IS state of the Co 3+ ions is rather small (it is about 180 K in temperature scale) [6 -8].

…”

mentioning

confidence: 99%

Possible ferromagnetic interactions between IS Co³⁺ ions in Nb doped cobaltites

Troyanchuk

Karpinsky

Szymczak

2005

Physica Status Solidi (b)

View full text Add to dashboard Cite

In LnCoO 3 oxides (Ln-lanthanide) Co ions in the ground state are characterized by the low spin electronic configuration t ) with temperature enhancement [1][2][3][4][5]. For example, the spin state of cobalt ions in LaCoO 3 gradually changes from LS to IS with temperature increment in the temperature range of 40-100 K.The energy difference between LS and IS state of the Co 3+ ions is rather small (it is about 180 K in temperature scale) [6 -8]. Usually this energy difference (δE) increases with reduction of the CoO 6 octahedron volume, so it is possible to control δE, changing the mean ionic radius of Ln 3+. As a rule, the LS → IS transition temperature slightly increases in LnCoO 3 solutions with Ln 3+ ionic radius reduction [9 -11]. External pressure can also lead to low spin state stabilization [12]. The Sr 2+ ionic radius is significantly greater than that of the La 3+ ion, so it is possible to expect stabilization of the intermediate spin state of cobalt ions by substituting Sr 2+ ions for La 3+ ones. However, at such heterovalent substitution Co 4+ ions appear, leading to the ferromagnetic metallic ground state [13][14][15]. The origin of the ferromagnetic state in metallic cobaltites and manganites has been a subject of discussion for a long time [16].

show abstract

Spin-state transition and microscopic magnetic properties of LaCoO3

Cited by 11 publications

References 7 publications

63,65Cu NMR investigation ofCuGeO
Fagot‐Revurat
¹
,
Horvatic-acute
²
,
Berthier
³

et al. 1997
Phys. Rev. B
29
4
15
0
View full text Add to dashboard Cite

63,65Cu NMR investigation ofCuGeO
Fagot‐Revurat
¹
,
Horvatic-acute
²
,
Berthier
³

et al. 1997
Phys. Rev. B
29
4
15
0
View full text Add to dashboard Cite

Itinerant metamagnetism and possible spin transition in LaCoO3 by temperature/hole doping

Possible ferromagnetic interactions between IS Co³⁺ ions in Nb doped cobaltites

Contact Info

Product

Resources

About

Spin-state transition and microscopic magnetic properties of LaCoO3

Cited by 11 publications

References 7 publications

63,65Cu NMR investigation ofCuGeOFagot‐Revurat1, Horvatic-acute2, Berthier3 et al. 1997Phys. Rev. B294150View full textAdd to dashboardCite

63,65Cu NMR investigation ofCuGeOFagot‐Revurat1, Horvatic-acute2, Berthier3 et al. 1997Phys. Rev. B294150View full textAdd to dashboardCite

Itinerant metamagnetism and possible spin transition in LaCoO3 by temperature/hole doping

Possible ferromagnetic interactions between IS Co3+ ions in Nb doped cobaltites

Contact Info

Product

Resources

About

63,65Cu NMR investigation ofCuGeO
Fagot‐Revurat
¹
,
Horvatic-acute
²
,
Berthier
³

et al. 1997
Phys. Rev. B
29
4
15
0
View full text Add to dashboard Cite

63,65Cu NMR investigation ofCuGeO
Fagot‐Revurat
¹
,
Horvatic-acute
²
,
Berthier
³

et al. 1997
Phys. Rev. B
29
4
15
0
View full text Add to dashboard Cite

Possible ferromagnetic interactions between IS Co³⁺ ions in Nb doped cobaltites