Electronic transport and thermal properties of CaB6 and Eu1−xCaxB6

Vonlanthen, P.; Felder, E.; Wälti, Ch.; Paschen, S.; Ott, H. R.; Young, David P.; Bianchi, Andrea; Fisk, Z.

doi:10.1016/s0921-4526(99)02501-6

Cited by 10 publications

(20 citation statements)

References 2 publications

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“…Previous studies on the specific heat of CaB 6 were restricted to low temperatures (below 20 K) [7,28,29]. In the current work, the specific capacity of CaB 6 from 2 K to room temperature was measured.…”

Section: Resultsmentioning

confidence: 92%

“…This peculiar magnetic property has motivated numerous investigations into the properties of CaB 6 crystals. In most studies on the physical or chemical properties of CaB 6 crystals, polycrystalline compounds [2−5] or single crystals were prepared by the flux-growth method [6][7][8], an approach that has many advantages, including simple experiment conditions and ease of obtaining larger single crystals, among others. However, this method presents the unavoidable disadvantage of the flux medium easily introducing impurities into the CaB 6 crystals, such as Al in the case of the aluminum-flux-growth method [9].…”

Section: Introductionmentioning

confidence: 99%

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Properties of CaB6 single crystals synthesized under high pressure and temperature

Xin

Liu

Zhao

et al. 2011

Sci. China Phys. Mech. Astron.

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Pure CaB 6 single crystals are synthesized under high pressure (1 GPa) and temperature (1050°C). The temperature-dependence of electric resistivity and Hall coefficient from 2 to 300 K shows that the CaB 6 single crystals are conductors with semi-metallic behavior and electron carriers. Band structure calculations indicate that the conduction and valence bands meet at the X point at the Fermi level, which is consistent with the experimentally determined conducting behavior of CaB 6 single crystals. Calculations of state density suggest that the states at the Fermi level originate from the 2p orbital of the B atoms and the 3d orbital of the Ca atom. Magnetization measurements show the paramagnetic nature of the CaB 6 . The micro-hardness of CaB 6 is 24.39 GPa, and the Raman spectra of CaB 6 yield three sharp peaks at around 780.9, 1138.9, and 1282.1 cm −1 for T 2g , E g , and A 1g , respectively. The specific heat of the crystal is measured and found to be well described by the Debye and Einstein combined model. The fitting results show Debye and Einstein temperatures are 1119 and 199 K, respectively. high pressure, CaB 6 , semi-metallic, single crystals PACS: 75.40.-s, 72.15.-v, 78.30.-j

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Section: Resultsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Properties of CaB6 single crystals synthesized under high pressure and temperature

Xin

Liu

Zhao

et al. 2011

Sci. China Phys. Mech. Astron.

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“…[11], they need not be intrinsically magnetic. Jarlborg [59,60] [64], that their CaB 6 samples were contaminated with Al granules. It therefore appears that Al does enter the bulk during Al flux growth and might also substitute for Ca.…”

Section: B Further Discussion Of Theory and Experimentsmentioning

confidence: 99%

“…However Monnier and Delley [61] find that the formation energy of a Ca vacancy and an Al substitutional impurity are both about 5eV , so that the defect concentrations would be negligible if growth took place under conditions of thermal equilibrium. This is probably not the case since it is generally believed that hexaborides, including CaB 6 , have a tendency to self-doping by metal vacancies [10,33,36,46,64,65]. It might be that certain non-magnetic impurities, including those in 3N boron which are apparently essential for ferromagnetism according to Cho et al [11], facilitate the formation of Ca vacancies or Al substitutional impurities by kinetic effects during growth, as suggested by Monnier and Delley [61] in connection with B 6 vacancies.…”

Section: B Further Discussion Of Theory and Experimentsmentioning

confidence: 99%

High-temperature ferromagnetism of sp electrons in narrow impurity bands: application to CaB₆

Edwards

Katsnelson

2006

J. Phys.: Condens. Matter

154

139

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Ferromagnetism with high Curie temperature T c , well above room temperature, and very small saturation moment has been reported in various carbon and boron systems. It is argued that the magnetization must be very inhomogeneous with only a small fraction of the sample ferromagnetically ordered. It is shown that a possible source of high T c within the ferromagnetic regions is itinerant electrons occupying a narrow impurity band. Correlation effects do not reduce the effective interaction which enters the Stoner criterion in the same way as in a bulk band. It is also shown how, in the impurity band case, spin wave excitations may not be effective in lowering T c below its value given by Stoner theory. These ideas are applied to CaB 6 and a thorough review of the experimental situation in this material is given. It is suggested that the intrinsic magnetism of the B 2 and O 2 dimers might be exploited in suitable structures containing these elements.

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“…The crystal structure of LaB 6 is a simple cubic CsCl-type arrangement of B 6octahedra and metal ions [1][2][3][4][5], and the electric conduction of LaB 6 shows metallic properties [7]. In addition, the electrical properties of hexaborides including various metal ions show a wide variation from semiconductor to superconductor [10], by doping divalent or trivalent ions into the crystal structure [11,12].…”

Section: Introductionmentioning

confidence: 99%

Fabrication and Characterization of Electrically Functional Lanthanum Hexaboride Thin Films on Ultrasmooth Sapphire Substrates

et al. 2008

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The crystal growth of lanthanum hexaboride (LaB6) thin films was examined by applying the laser molecular beam epitaxy (laser MBE) process. C-axis (100) highly-oriented LaB6 thin films could be fabricated on ultrasmooth sapphire (α-Al2O3 single crystal) (0001) substrates with atomic steps of 0.2 nm in height and atomically flat terraces. The obtained film exhibited a smooth surface with root mean square roughness of 0.15 nm. The lattice parameter of the LaB6 thin film was close to the bulk value reported previously. In the case of deposition on commercial mirror-polished sapphire substrates, the grown film was amorphous. The resistivity of the prepared crystalline LaB6 thin films was as low as 2.2 × 10−4 Ω cm and almost constant in the temperature range of 10–300 K.

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Electronic transport and thermal properties of CaB6 and Eu1−xCaxB6

Cited by 10 publications

References 2 publications

Properties of CaB6 single crystals synthesized under high pressure and temperature

Properties of CaB6 single crystals synthesized under high pressure and temperature

High-temperature ferromagnetism of sp electrons in narrow impurity bands: application to CaB₆

Fabrication and Characterization of Electrically Functional Lanthanum Hexaboride Thin Films on Ultrasmooth Sapphire Substrates

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Electronic transport and thermal properties of CaB6 and Eu1−xCaxB6

Cited by 10 publications

References 2 publications

Properties of CaB6 single crystals synthesized under high pressure and temperature

Properties of CaB6 single crystals synthesized under high pressure and temperature

High-temperature ferromagnetism of sp electrons in narrow impurity bands: application to CaB6

Fabrication and Characterization of Electrically Functional Lanthanum Hexaboride Thin Films on Ultrasmooth Sapphire Substrates

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High-temperature ferromagnetism of sp electrons in narrow impurity bands: application to CaB₆