Magnetic and transport properties of pure and carbon-doped divalent RE hexaboride single crystals

Tarascon, Jean‐Marie; Étourneau, J.; Dordor, P.; Hagenmuller, Paul; Koshi, Mitsuo; Coey, J. M. D.

doi:10.1063/1.327309

Cited by 89 publications

(64 citation statements)

References 10 publications

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“…We first consider the case of YbB 6 where the RE element is divalent. It has been reported that although YbB 6 single crystals may show metallic behavior in resistivity measurements at low temperature, defect-free YbB 6 would behave as an intrinsic semiconductor with a finite energy gap between the 5d and 2p bands [48]. The metallic behavior of YbB 6 is then ascribed to the formation of impurity bands [48].…”

Section: Resultsmentioning

confidence: 99%

Comparative study of rare earth hexaborides using high resolution angle-resolved photoemission

Ramankutty

Jong

Huang

et al. 2016

Journal of Electron Spectroscopy and Related Phenomena

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Strong electron correlations in rare earth hexaborides can give rise to a variety of interesting phenomena like ferromagnetism, Kondo hybridization, mixed valence, superconductivity and possibly topological characteristics. The theoretical prediction of topological properties in SmB6 and YbB6, has rekindled the scientific interest in the rare earth hexaborides, and high-resolution ARPES has been playing a major role in the debate. The electronic band structure of the hexaborides contains the key to understand the origin of the different phenomena observed, and much can be learned by comparing the experimental data from different rare earth hexaborides. We have performed high-resolution ARPES on the (001) surfaces of YbB6, CeB6 and SmB6. On the most basic level, the data show that the differences in the valence of the rare earth element are reflected in the experimental electronic band structure primarily as a rigid shift of the energy position of the metal 5d states with respect to the Fermi level. Although the overall shape of the d-derived Fermi surface contours remains the same, we report differences in the dimensionality of these states between the compounds studied. Moreover, the spectroscopic fingerprint of the 4f states also reveals considerable differences that are related to their coherence and the strength of the d-f hybridization. For the SmB6 case, we use ARPES in combination with STM imaging and electron diffraction to reveal time dependent changes in the structural symmetry of the highly debated SmB6(001) surface. All in all, our study highlights the suitability of electron spectroscopies like high-resolution ARPES to provide links between electronic structure and function in complex and correlated materials such as the rare earth hexaborides.

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Section: Resultsmentioning

confidence: 99%

Comparative study of rare earth hexaborides using high resolution angle-resolved photoemission

Ramankutty

Jong

Huang

et al. 2016

Journal of Electron Spectroscopy and Related Phenomena

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“…This correlated topological phase in YbB 6 has been proposed to be explainable by an adjustable correlation parameter (Hubbard-U ) and a band inversion between the d and p bands under a nonzero Coulomb interaction value [15]. Moreover, the rare-earth hexaborides can provide a platform to realize a rich variety of distinct electronic ground states such as ferromagnetic order in EuB 6 and superconductivity in LaB 6 (T c ∼ 0.5 K) [4,16,17].…”

Section: Pacs Numbersmentioning

confidence: 99%

“…Single crystal samples of CeB 6 and BaB 6 used in our measurements were grown in the Fisk lab at the University of California (Irvine) by the Al-flux method, which is detailed elsewhere [12,16]. Synchrotron-based ARPES measurements of the electronic structure were performed at the Beamlines 4.0.3 and 10.0.1 of the Advanced Light Source, Berkeley, CA equipped with high-efficiency Scienta R8000 electron analyzers and beamline I4 of MAX-LAB III, Lund, Sweden equipped with a SPECS Phoibos 100 anlyzer.…”

Section: Pacs Numbersmentioning

confidence: 99%

Fermi surface topology and hot spot distribution in the Kondo lattice systemCeB6

et al. 2015

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Rare-earth hexaborides have attracted a considerable attention recently in connection to variety of correlated phenomena including heavy fermions, superconductivity and low temperature magnetic phases. Here, we present high-resolution angle-resolved photoemission spectroscopy studies of trivalent CeB 6 and divalent BaB 6 rare-earth hexaborides. We find that the Fermi surface electronic structure of CeB 6 consists of large oval-shaped pockets around the X points of the Brillouin zone, while the states around the zone center Γ point are strongly renormalized. Our first-principles calculations agree with our experimental results around the X points, but not around the Γ point, indicating areas of strong renormalization located near Γ. The Ce quasi-particle states participate in the formation of hotspots at the Fermi surface, while the incoherent f states hybridize and lead to the emergence of dispersive features absent in the non-f counterpart BaB 6 . Our results provide a new understanding of the electronic structure in rare-earth hexaborides, which will be useful in elucidating the nature of the exotic low-temperature phases in these materials.

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“…36 Experimental data, however, do not support these theoretical predictions. [26][27][28]37 . Recent ARPES experiments [26][27][28] show that Yb-4f states are located at ∼ -1 eV and -2.3 eV below E F , indicating that YbB 6 does not belong to the Kondo insulator paradigm.…”

Section: Electronic Structure Of Ybb6mentioning

confidence: 99%

“…Early transport measurements indicated that YbB 6 is a doped semiconductor 37 . Recent ARPES experiments [26][27][28] however find that the Yb-4f states lie ∼ 1 eV below the E F , suggesting a non-TKI phase, contradicting theoretical predictions.…”

Section: Introductionmentioning

confidence: 99%

Two distinct topological phases in the mixed-valence compoundYbB6and its differences fromSmB6

et al. 2015

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We discuss the evolution of topological states and their orbital textures in the mixed valence compounds SmB6 and YbB6 within the framework of the generalized gradient approximation plus onsite Coulomb interaction (GGA+U) scheme for a wide range of values of U . In SmB6, the topological Kondo insulator (TKI) gap is found to be insensitive to the value of U , but in sharp contrast, Kondo physics in isostructural YbB6 displays a surprising sensitivity to U . In particular, as U is increased in YbB6, the correlated TKI state in the weak-coupling regime transforms into a d − p-type topological insulator phase with a band inversion between Yb-5d and B-2p orbitals in the intermediate coupling range, without closing the insulating energy gap throughout this process. Our theoretical predictions related to the TKI and non-TKI phases in SmB6 and YbB6 are in substantial accord with recent angle-resolved photoemission spectroscopy (ARPES) experiments.

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Magnetic and transport properties of pure and carbon-doped divalent RE hexaboride single crystals

Cited by 89 publications

References 10 publications

Comparative study of rare earth hexaborides using high resolution angle-resolved photoemission

Comparative study of rare earth hexaborides using high resolution angle-resolved photoemission

Fermi surface topology and hot spot distribution in the Kondo lattice systemCeB6

Two distinct topological phases in the mixed-valence compoundYbB6and its differences fromSmB6

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