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Mabatah, A. K.; Yoffa, Ellen J.; Eklund, P. C.; Dresselhaus, M. S.; Adler, David

doi:10.1103/physrevb.21.1676

Cited by 28 publications

(13 citation statements)

References 31 publications

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“…By contrast, ␣ is large and positive when the Mott-Hubbard subbands are formed in the semiconducting range, and ␣ is also numerically small at low temperatures. The interpretation of the Seebeck coefficients ␣ in NiS 2Ϫx Se x and Ni 1Ϫy Cu y S 2 as provided by Adler and co-workers 11,30,31 was based on a oneband electron correlation theory described in their publications. An excellent data fit was achieved by use of this sixparameter model for temperatures in excess of the peak temperature T m , including changes in sign at elevated temperatures.…”

Section: B Seebeck Measurementsmentioning

confidence: 99%

Electrical properties ofNiS2−xSexsingle crystals: From Mott insulator to par

et al. 1996

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Electrical resistivity () and Seebeck-coefficient measurements (␣) are reported for NiS 2Ϫx Se x single crystals in the range 0рxр0.71. There is a general trend toward increasing metallicity with increasing x. In the range 0.38рxр0.51 a pronounced rise of with temperature (T) is observed where the antiferromagnetic insulating ͑or antiferromagnetic metallic͒ phase changes over to the paramagnetic insulating phase. The analysis of ␣ vs T curves suggests that in the low-temperature insulating state both holes and electrons participate in charge transport. It is emphasized that the many changes in electrical characteristics occur without significant alterations in the pyrite crystal structure, and that physical properties are greatly altered solely by adjustment of the anion sublattice while the cation sublattice remains intact. The results concerning electrical transport for the samples with 0.38рxр0.55 are interpreted qualitatively on the basis of an onset of the Hubbard splitting into subbands at the transition to the insulating ͑semiconducting͒ state, which takes place in the temperature interval ͑50-100 K͒ upon heating the samples. The metallic state close to the metalsemiconductor boundary is viewed as being an antiferromagnetic semimetal, with an anisotropic Slater gap.

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Section: B Seebeck Measurementsmentioning

confidence: 99%

Electrical properties ofNiS2−xSexsingle crystals: From Mott insulator to par

et al. 1996

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“…When carriers interactions are not screened out, as in the less conducting specimens, the on-site correlation effects are appreciable. This estimate of U is comparible to that encountered in the Nii_ x CoxS2 system investigated by Mabatah et al 66 .…”

Section: Transport Propertiesmentioning

confidence: 69%

Synthesis, Structure, and Properties of La₂NiO_4+δ

Buttrey

Honig

1991

Chemistry of High Temperature Superconductors

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An overview of literature covering the preparation and characterization of La 2 Ni0 4+ g is presented in view of the close relationship to the layered cuprates. Particular emphasis is placed on the sensitive dependence of structure and physical properties on die concentration of excess lattice oxygen, S. The La 2 Ni0 4+ £ phase diagram exhibits structural, antiferromagnetic and metal/insulator phase transitions and at contains at least one phase separation region, similar to the La 2 Cu0 4+ g system. Whereas the structure and magnetic properties of the stoichiometric composition are reasonably well established, significant discrepancies exist with regard to the evolution of behavior with increasing oxygen content.The extraordinary worldwide interest in high-7"c superconductivity, as manifested in La 2 . x (Sr,Ba) x Cu0 4 and other layered systems, has sparked renewed interest in the physical properties of their closely related nickel analogs. In this article we offer a brief review of the preparation, structure, and physical properties of La 2 Ni0 4+ £; due to space limitations it was not possible (except in a few instances) to extend the discussion to alloy systems such as La 2 . x (Sr,Ba) x Ni0 4 , or to other rare earth materials of composition Ln 2 Ni0 4 . Research on the structure and physical properties of the layered perovskites of nickel was pursued at a relatively low level of effort through the early eighties, but has significantly accelerated in last few years. Earlier reviews, particularly in the context of relating lanthanide nickelates to other oxides possessing the K 2 NiF 4 structure, have been published

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“…The description of its electronic structure has evolved with time. NiS2 was first described as a prototypical example of a Mott-Hubbard insulator [2][3][4][5][6][7]. More recently, theory and experimental (photoemission) studies [8,9] pointed towards a charge-transfer insulator with a band gap between the S anion 3p band at the highest valence states and Ni 3d states at the bottom of the conduction band.…”

Section: -Introductionmentioning

confidence: 99%

“…Although most of the studies in line with the Mott-Hubbard scenario interpreted the effect of Co (or Cu) for Ni substitution in NiS2 as a way to remove (or add) electrons in the half-filled eg broad band [3][4][5], most recent ones pointed towards a possible charge disproportionation as the mechanism responsible for the insulating state [15]. The NiS2 magnetic behaviour is complex, with two different commensurate antiferromagnetic (AF) states, M1, below TN1 = 39.2 K, and M2, below TN2 = 29.75 K [15].…”

Section: -Introductionmentioning

confidence: 99%

Thermoelectric properties, metal-insulator transition, and magnetism: Revisiting the Ni1−xCuxS2

Maignan

Daou

Guilmeau

et al. 2019

Phys. Rev. Materials

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The Ni1-xCuxS2 pyrite (x ≤ 0.07) is a model material where the impact of electron filling on a half-filled eg band system can be separated from changes in the bandwidth, since the unit cell volume does not change with x.This contrasts with the NiS2-xSex system where the size difference between S 2and Se 2makes the bandwidth vary at constant band filling. Our magnetic measurements show that there exists a clear relation between the presence of the antiferromagnetic phase developing below TN2 = 29.75 K and charge localization. With the addition of Cu in Ni1-xCuxS2, the ground state evolves towards a metallic paramagnetic state. These new findings are discussed with the scenario based on charge ordering at low temperature in the charge transfer insulator NiS2 pyrite, and also considering possible conducting surface states at low temperatures. At 300 K, the thermal conductivity decreases by 2.5 as x increases from 0.00 to 0.07, even though the latter is much more electrically conductive than the former. This considerably extends the range of values for the thermal conductivity of the MS2 pyrites, from the largest in FeS2 to the lowest in the present Ni1-xCuxS2 samples.

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Electrical properties ofNi1−xCoxS

Cited by 28 publications

References 31 publications

Electrical properties ofNiS2−xSexsingle crystals: From Mott insulator to par

Electrical properties ofNiS2−xSexsingle crystals: From Mott insulator to par

Synthesis, Structure, and Properties of La₂NiO_4+δ

Thermoelectric properties, metal-insulator transition, and magnetism: Revisiting the Ni1−xCuxS2

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Electrical properties ofNi1−xCoxS

Cited by 28 publications

References 31 publications

Electrical properties ofNiS2−xSexsingle crystals: From Mott insulator to par

Electrical properties ofNiS2−xSexsingle crystals: From Mott insulator to par

Synthesis, Structure, and Properties of La2NiO4+δ

Thermoelectric properties, metal-insulator transition, and magnetism: Revisiting the Ni1−xCuxS2

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Synthesis, Structure, and Properties of La₂NiO_4+δ