Observation of low, intermediate, and high spin states in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">GdBaCo</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>5.45</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

Roy, Sujoy; Khan, Mahmud; Guo, Yuqiao; Craig, J.; Ali, Naushad

doi:10.1103/physrevb.65.064437

Cited by 83 publications

(66 citation statements)

References 13 publications

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“…1,2,3,4,5,6,7 During the last years cobaltates with layered CoO structures have also become subject of intense studies. 8,9,10,11,12,13,14,15 It has been proposed that various of these compounds would also show temperature-dependent spin-state transitions of the Co 3+ and/or Co 2+ ions, but an unambiguous proof of such spin-state transitions is still missing (see e. g. Ref. 15).…”

Section: Introductionmentioning

confidence: 99%

Thermal conductivity, thermopower, and figure of merit ofLa1−xSrxCoO3

Berggold¹,

Kriener²,

Zobel³

et al. 2005

Phys. Rev. B

116

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We present a study of the thermal conductivity κ and the thermopower S of single crystals of La1−xSrxCoO3 with 0 ≤ x ≤ 0.3. For all Sr concentrations La1−xSrxCoO3 has rather low κ values. For the insulators (x < 0.18) this arises from a suppression of the phonon thermal conductivity by lattice disorder due to temperature-and/or doping-induced spin-state transitions of the Co ions. For larger x, the heat transport by phonons remains low, but an additional contribution from mobile charge carriers causes a moderate increase of κ. The thermopower of the low-doped crystals is positive and shows a pronounced maximum as a function of temperature. With increasing x, this maximum strongly broadens and its magnitude decreases. For the highest Sr content (x = 0.3) S becomes even negative in the intermediate temperature range. From S, κ, and the electrical resistivity ρ we derive the thermoelectric figure of merit Z = S 2 / κρ. For intermediate Sr concentrations we find notably large values of Z indicating that Co-based materials could be promising candidates for thermoelectric cooling.

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Section: Introductionmentioning

confidence: 99%

Thermal conductivity, thermopower, and figure of merit ofLa1−xSrxCoO3

Berggold¹,

Kriener²,

Zobel³

et al. 2005

Phys. Rev. B

116

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“…After the discovery of the "112" ordered oxygen deficient perovskites LnBaCo 2 O 5.4 (Ln = Eu, Gd), with original metal-insulator and ferroantiferromagnetic transitions coupled with giant magnetoresistance [1], numerous studies were carried out to understand the attractive physics of the LnBaCo 2 O 5+x oxides structure [2][3][4][5][6][7][8][9][10][11][12]. In this series, the oxides corresponding to Ln = Eu, Gd and Tb exhibit a very similar behavior, due to the fact that the oxygen content corresponding to the ideal formula LnBaCo 2 O 5.5 , can be more easily controlled, just by synthesizing the compounds in air.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of ferromagnetism by nickel doping in the ‘112’ cobaltite EuBaCo₂O_5.50

Raveau¹,

Simon²,

Caignaert³

et al. 2006

J. Phys.: Condens. Matter

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The study of the ordered oxygen deficient perovskite EuBaCo 2-x Ni x O 5.50 shows that the doping of cobalt sites by nickel induces a strong ferromagnetic component at low temperature in the antiferromagnetic matrix of EuBaCo 2 O 5.50 . This system exhibits indeed phase separation, i.e. consists of ferromagnetic domains embedded in the antiferromagnetic matrix of EuBaCo 2 O 5.50 . Besides, a magnetic transition is observed for the first time at 40K in the undoped and nickel doped phases, which can be attributed to the ferromagnetic ordering of the Eu 3+ moments below this temperature. Moreover sharp ultra magnetization multisteps are observed below 5K, characteristic of motion of domain walls in a "strong pinning" system and very different from any metamagnetic transition.

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“…The value of T S1 measured for GdBaCo 2 O 5.47 (2) is close to the metal-insulator transition T MI = 359 K for the same oxygen content [7]. Since the transport properties should depend on the orbital ordering [8], the second objective is to verify whether these critical temperatures coincide when measured for the same crystal in identical temperature conditions.…”

Section: Introductionmentioning

confidence: 99%

X-ray and neutron diffraction studies of coupled structural phase transitions in DyBaCo2O5.5

et al. 2007

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A structural transition at T ≈ 322 K from the P mmm to P mma phase is found to coincide with an anomaly of resistivity. Another structural phase transition doubling the lattice parameter c, which has been postulated earlier to accompany a low-temperature magnetic transition in TbBaCo2O5.5, is observed in a single crystal DbBaCo2O5.5 by means of the X-ray and neutron diffraction. The low temperature phase does not belong to the space group P cca that has been chosen earlier as the highest subgroup of the P mma. The transition is of the first order with the temperature hysteresis, between T ≈ 100 and T ≈ 200 K, which probably explains anomalous magnetic properties in this temperature range.

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Observation of low, intermediate, and high spin states inGdBaCo2O5.45

Cited by 83 publications

References 13 publications

Thermal conductivity, thermopower, and figure of merit ofLa1−xSrxCoO3

Thermal conductivity, thermopower, and figure of merit ofLa1−xSrxCoO3

Enhancement of ferromagnetism by nickel doping in the ‘112’ cobaltite EuBaCo₂O_5.50

X-ray and neutron diffraction studies of coupled structural phase transitions in DyBaCo2O5.5

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Observation of low, intermediate, and high spin states inGdBaCo2O5.45

Cited by 83 publications

References 13 publications

Thermal conductivity, thermopower, and figure of merit ofLa1−xSrxCoO3

Thermal conductivity, thermopower, and figure of merit ofLa1−xSrxCoO3

Enhancement of ferromagnetism by nickel doping in the ‘112’ cobaltite EuBaCo2O5.50

X-ray and neutron diffraction studies of coupled structural phase transitions in DyBaCo2O5.5

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Enhancement of ferromagnetism by nickel doping in the ‘112’ cobaltite EuBaCo₂O_5.50