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Magnetic transitions in the 1D chain compounds NdPd 5Ge 3and NdPt 5Ge 3. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:435801. [PMID: 34330127 DOI: 10.1088/1361-648x/ac196a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 07/30/2021] [Indexed: 06/13/2023]
Abstract
We present the structural and initial magnetic characterization of the previously unreported materials NdPd5Ge3and NdPd5Ge3. These materials, with one-dimensional Nd chains, crystallize in the orthorhombic YNi5Si3-type structure in space groupPnma. Magnetic ordering is observed for both compounds at ∼2.2 K for NdPd5Ge3and ∼3.0 K for NdPt5Ge3. A magnetic-field-induced transition is clearly observed for NdPd5Ge3below 2 K, at an applied magnetic field of around 1.6 T. The heat capacity data reveals that essentially all the available magnetic entropy is released at the magnetic ordering transition for NdPd5Ge3but that only 29% is seen for NdPt5Ge3at temperatures down to 1.5 K, the data implying that a second magnetic transition can be expected at lower temperatures.
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Abstract
While electronic states with nontrivial topology have traditionally been known in insulators, they have been evidenced in metals during the past 2 years. Such Weyl semimetals show topological protection while conducting electricity both in the bulk and on the surface. An outstanding question is whether topological protection can happen in metals with strong correlations. Here, we report theoretical work on a strongly correlated lattice model to demonstrate the emergence of a Weyl–Kondo semimetal. We identify Weyl fermions in the bulk and Fermi arcs on the surface, both of which are associated with the many-body phenomenon called the Kondo effect. We determine a key signature of this Weyl–Kondo semimetal, which is realized in a recently discovered heavy-fermion compound. Insulating states can be topologically nontrivial, a well-established notion that is exemplified by the quantum Hall effect and topological insulators. By contrast, topological metals have not been experimentally evidenced until recently. In systems with strong correlations, they have yet to be identified. Heavy-fermion semimetals are a prototype of strongly correlated systems and, given their strong spin-orbit coupling, present a natural setting to make progress. Here, we advance a Weyl–Kondo semimetal phase in a periodic Anderson model on a noncentrosymmetric lattice. The quasiparticles near the Weyl nodes develop out of the Kondo effect, as do the surface states that feature Fermi arcs. We determine the key signatures of this phase, which are realized in the heavy-fermion semimetal Ce3Bi4Pd3. Our findings provide the much-needed theoretical foundation for the experimental search of topological metals with strong correlations and open up an avenue for systematic studies of such quantum phases that naturally entangle multiple degrees of freedom.
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Rearrangement of van der Waals stacking and formation of a singlet state at T = 90 K in a cluster magnet. Inorg Chem Front 2017. [DOI: 10.1039/c6qi00470a] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
A change of van der Waals stacking occurs spontaneously at 90 K in a cluster magnet.
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Cerium intermetallics with TiNiSi-type structure. ZEITSCHRIFT FUR NATURFORSCHUNG SECTION B-A JOURNAL OF CHEMICAL SCIENCES 2016. [DOI: 10.1515/znb-2016-0101] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Intermetallic compounds with the equiatomic composition CeTX that crystallize with the orthorhombic TiNiSi-type structure can be synthesized with electron-rich transition metals (T) and X = Zn, Al, Ga, Si, Ge, Sn, As, Sb, and Bi. The present review focusses on the crystal chemistry and chemical bonding of these CeTX phases and on their physical properties, 119Sn and 121Sb Mössbauer spectra, high-pressure effects, hydrogenation reactions and the formation of solid solutions in order to elucidate structure–property relationships. This paper is the final one of a series of four reviews on equiatomic intermetallic cerium compounds [Part I: Z. Naturforsch. 2015, 70b, 289; Part II: Z. Naturforsch. 2015, 70b, 695; Part III: Z. Naturforsch. 2016, 71b, 165].
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CeRu4Sn6: a strongly correlated material with nontrivial topology. Sci Rep 2015; 5:17937. [PMID: 26658647 PMCID: PMC4674697 DOI: 10.1038/srep17937] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 11/09/2015] [Indexed: 11/08/2022] Open
Abstract
Topological insulators form a novel state of matter that provides new opportunities to create unique quantum phenomena. While the materials used so far are based on semiconductors, recent theoretical studies predict that also strongly correlated systems can show non-trivial topological properties, thereby allowing even the emergence of surface phenomena that are not possible with topological band insulators. From a practical point of view, it is also expected that strong correlations will reduce the disturbing impact of defects or impurities, and at the same increase the Fermi velocities of the topological surface states. The challenge is now to discover such correlated materials. Here, using advanced x-ray spectroscopies in combination with band structure calculations, we infer that CeRu4Sn6 is a strongly correlated material with non-trivial topology.
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Dynamical magnetic correlations in the YbB12 kondo insulator: Neutron investigations with a polarization analysis. CRYSTALLOGR REP+ 2007. [DOI: 10.1134/s1063774507030066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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First-order transition between a small gap semiconductor and a ferromagnetic metal in the isoelectronic alloy FeSi1-xGex. PHYSICAL REVIEW LETTERS 2002; 89:257203. [PMID: 12484913 DOI: 10.1103/physrevlett.89.257203] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2002] [Indexed: 05/24/2023]
Abstract
The contrasting ground states of isoelectronic, isostructural FeSi and FeGe are explained within an extended local density approximation scheme (LDA+U) by an appropriate choice of the Coulomb repulsion U on the Fe sites. A minimal two-band model with interband interactions leads to a phase diagram for the alloys FeSi1-xGex. A mean field approximation gives a first-order transition between a small gap semiconductor and a ferromagnetic metal as a function of magnetic field, temperature, and concentration x. Unusually the transition from metal to insulator is driven by broadening, not narrowing, the bands and it is the metallic state that shows magnetic order.
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Charge ordering and spin dynamics in NaV(2)O(5). PHYSICAL REVIEW LETTERS 2001; 86:5966-5969. [PMID: 11415405 DOI: 10.1103/physrevlett.86.5966] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2000] [Indexed: 05/23/2023]
Abstract
We report high-resolution neutron inelastic scattering experiments on the spin excitations of NaV(2)O(5). Below T(c), two branches with distinct energy gaps are identified. From the dispersion and intensity of the spin excitation modes, we deduce the precise zigzag charge distribution on the ladder rungs and the corresponding charge order: Delta(c) approximately 0.6. We argue that the spin gaps observed in the low-T phase of this compound are primarily due to the charge transfer.
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Chapter 206 μSR studies of rare-earth and actinide magnetic materials. HANDBOOK ON THE PHYSICS AND CHEMISTRY OF RARE EARTHS 2001. [DOI: 10.1016/s0168-1273(01)32005-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Gap-anisotropic model for the narrow-Gap kondo insulators. PHYSICAL REVIEW LETTERS 2000; 84:342-345. [PMID: 11015906 DOI: 10.1103/physrevlett.84.342] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/1998] [Indexed: 05/23/2023]
Abstract
A theory is presented which accounts for the dynamical generation of a hybridization gap with nodes in the Kondo insulating materials CeNiSn and CeRhSb. We show that Hund's interactions acting on virtual 4f(2) configurations of the cerium ion can act to dynamically select the shape of the cerium ion by generating a Weiss field which couples to the shape of the ion. In low symmetry crystals where the external crystal fields are negligible, this process selects a nodal Kondo semimetal state as the lowest energy configuration.
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Electric-field gradient at the Fe nucleus in epsilon -FeSi. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:15985-15990. [PMID: 9985668 DOI: 10.1103/physrevb.54.15985] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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The effect of Co doping on antiferromagnetic correlations in the Kondo semi-metal CeNiSn. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 1996; 8:7127-7138. [PMID: 22146154 DOI: 10.1088/0953-8984/8/38/015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Single-crystal neutron scattering experiments have been performed to study magnetic excitations in [Formula: see text], in which the pseudo-gap of CeNiSn is suppressed by the doping. In CeNiSn there are two inelastic excitation peaks at [Formula: see text] and 4 meV, which correspond to dynamic antiferromagnetic correlations. In [Formula: see text] the 2 meV peak is smeared out, whereas the 4 meV peak becomes very weak and broad, but preserves the same quasi-one-dimensional character as that for CeNiSn. These results suggest the strong relation between the antiferromagnetic correlations and the pseudo-gap formation.
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Quantum fluctuations in the Kondo insulators: Slave-boson approach. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:R728-R731. [PMID: 9985420 DOI: 10.1103/physrevb.54.r728] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Impurity and doping effects on the pseudoenergy gap in CeNiSn: A Sn NMR study. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:6385-6392. [PMID: 9982035 DOI: 10.1103/physrevb.53.6385] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Tunneling Evidence for the Quasiparticle Gap in Kondo Semiconductors CeNiSn and CeRhSb. PHYSICAL REVIEW LETTERS 1995; 75:4262-4265. [PMID: 10059860 DOI: 10.1103/physrevlett.75.4262] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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High magnetic fields and the correlation gap in SmB6. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:7322-7327. [PMID: 9979675 DOI: 10.1103/physrevb.52.7322] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Kondo insulators modeled by the one-dimensional Anderson lattice: A numerical-renormalization-group study. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:10301-10312. [PMID: 9977723 DOI: 10.1103/physrevb.51.10301] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Competition between antiferromagnetic order and spin-liquid behavior in the two-dimensional periodic Anderson model at half filling. PHYSICAL REVIEW LETTERS 1995; 74:2367-2370. [PMID: 10057910 DOI: 10.1103/physrevlett.74.2367] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Electronic structures of CeNiSn, CePdSn, and CePtSn. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:2994-3002. [PMID: 9979079 DOI: 10.1103/physrevb.51.2994] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Transport properties of Kondo holes in a Kondo insulator. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:2576-2579. [PMID: 9979016 DOI: 10.1103/physrevb.51.2576] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Low-temperature magnetic, thermal, and transport properties of FeSi. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:14933-14941. [PMID: 9975839 DOI: 10.1103/physrevb.50.14933] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Alloying effects of Kondo insulators. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:11332-11339. [PMID: 9975263 DOI: 10.1103/physrevb.50.11332] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Aspects of strongly correlated insulators. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:9952-9956. [PMID: 9975077 DOI: 10.1103/physrevb.50.9952] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Anisotropic physical properties of the Kondo semiconductor CeRhSb. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:623-626. [PMID: 9974595 DOI: 10.1103/physrevb.50.623] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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209Bi NMR and NQR investigation of the small-gap semiconductor Ce3Bi4Pt3. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:16321-16330. [PMID: 10010781 DOI: 10.1103/physrevb.49.16321] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Electronic structure and optical properties of FeSi, a strongly correlated insulator. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:2219-2222. [PMID: 10011042 DOI: 10.1103/physrevb.49.2219] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Anomalous specific heat of Ce1-xThxRhSb alloys. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:348-351. [PMID: 10009292 DOI: 10.1103/physrevb.49.348] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Chapter 130 Neutron inelastic scattering from actinides and anomalous lanthanides. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/s0168-1273(05)80059-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Numerical renormalization group study of the one-dimensional Kondo insulator. PHYSICAL REVIEW LETTERS 1993; 71:3866-3869. [PMID: 10055093 DOI: 10.1103/physrevlett.71.3866] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Band structure and semiconducting properties of FeSi. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 47:13114-13119. [PMID: 10005613 DOI: 10.1103/physrevb.47.13114] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Spin-triplet solitons in the one-dimensional symmetric Kondo lattice. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 47:11935-11939. [PMID: 10005365 DOI: 10.1103/physrevb.47.11935] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Competition between singlet formation and magnetic ordering in one-dimensional spin systems. PHYSICAL REVIEW LETTERS 1992; 69:2419-2422. [PMID: 10046480 DOI: 10.1103/physrevlett.69.2419] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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