Low-temperature properties of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>CeRu</mml:mtext></mml:mrow><mml:mn>4</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mtext>Sn</mml:mtext></mml:mrow><mml:mn>6</mml:mn></mml:msub></mml:mrow></mml:math>from NMR and specific heat measurements: Heavy fermions emerging from a Kondo-insulating state

Brüning, E. M.; Brando, M.; Baenitz, M.; Bentien, Anders; Strydom, A. M.; Walstedt, R. E.; Steglich, F.

doi:10.1103/physrevb.82.125115

Cited by 28 publications

(26 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Along the c direction only a minimum is clearly seen at T c min % 25 K, somewhat higher than T min for the in-plane directions. Thermopower data on polycrystalline CeRu 4 Sn 6 were published by Brü ning et al 9 They are included in Fig. 1 for comparison.…”

Section: Physical Propertiesmentioning

confidence: 99%

Anisotropic Thermopower of the Kondo Insulator $$\hbox {CeRu}_4\hbox {Sn}_6$$ CeRu 4 Sn 6

Hänel

Winkler

Ikeda

et al. 2014

Journal of Elec Materi

View full text Add to dashboard Cite

The intermetallic compound CeRu 4 Sn 6 has been tentatively classified as Kondo insulator. This class of material, especially non-cubic representatives,is not yet fully understood. Here we report thermopower measurements on single-crystalline CeRu 4 Sn 6 between 2 K and 650 K, along the main crystallographic directions. Large positive thermopower is observed in the directions along which the hybridization is strong and a Kondo insulating gap forms. A negative contribution to the thermopower dominates for the crystallographic c axis where hybridization is weak and metallicity prevails.

show abstract

Section: Physical Propertiesmentioning

confidence: 99%

Anisotropic Thermopower of the Kondo Insulator $$\hbox {CeRu}_4\hbox {Sn}_6$$ CeRu 4 Sn 6

Hänel

Winkler

Ikeda

et al. 2014

Journal of Elec Materi

View full text Add to dashboard Cite

show abstract

“…The electronic structure of CeRu 4 Sn 6 has been studied both theoretically and experimentally by several groups already. [29][30][31][32] As introduced in references [30, 31], the band structure obtained by local density approximation (LDA) is semimetal type with the vanishing indirect but finite direct energy gap between the valence band mostly consisting of Ruthenium 4d orbitals and conduction band formed mostly by the Cerium 4f orbitals. The LDA+DMFT calculation has been applied to this material by K. Held's group to capture the strong correlation effects.[32] Besides the reduction of the bandwidth for the f -bands, another significant consequence of the correlation effect is to enhance the crystal splitting within the J = 5/2 subspace and push down the lowest 4f bands with the J = 5/2, J z = ±1/2 character, which leads to "inverted features" between 4f and 4d bands in some area of the BZ mimicking the situation in SmB 6 .…”

mentioning

confidence: 99%

Heavy Weyl Fermion State in CeRu4Sn6

Yue

Weng

et al. 2017

Phys. Rev. X

View full text Add to dashboard Cite

A new type of topological state in strongly corrected condensed matter systems, heavy Weyl fermion state, has been found in a heavy fermion material CeRu4Sn6, which has no inversion symmetry . Both two different types of Weyl points, type I and II, can be found in the quasi-particle band structure obtained by the LDA+Guztwiller calculations, which can treat the strong correlation effects among the f-electrons from Cerium atoms. The surface calculations indicate that the topologically protected Fermi arc states exist on the (010) but not on the (001) surfaces.Recently different types of topological semimetals [1] have been proposed and observed in condensed matter systems, i.e. the Weyl semimetal(WSM) phase in transition metal compounds with the magnetic order, [2, 3] WSM phase in non-central symmetric crystals, [4-9] Dirac semimetal (DSM) phase in intermetallic compounds [10][11][12][13][14][15] and nodal line semimetal phase in anti-perovskite compounds. [16,17] In all the abovementioned material systems, the electron-electron correlation effect is weak, and the band structure, as well as the existence of Weyl nodes, can be obtained quite accurately by density functional theory. On the other hand, the topological non-trivial electronic structure can be found in strongly correlated material systems as well, for instance, the topological Kondo insulator phase in SmB 6 [18-20] can be viewed as the strongly correlated Z 2 topological insulator, which has attracted lots of research interests in recent years. [21][22][23][24][25] In SmB 6 , the correlation effects generated by the strong Coulomb repulsive interaction among f -electrons suppress the bandwidth dramatically but leave the topological features of the electronic structure unchanged [20,24,26,27].In the present letter, we propose that CeRu 4 Sn 6 , [28-32] a typical heavy fermion material, contains Weyl points in its quasiparticle band structure near the Fermi level and thus belongs to a new class of strongly correlated topological phase, heavy Weyl fermion state. Comparing to other WSMs found in non-interacting systems, the WSM phase in heavy fermion system has more fruitful physical properties due to the following reasons. Firstly, unlike the non-interacting systems, the heavy quasiparticle bands are fully developed only at the low temperature. Therefore, how the physics related to the topological electronic structure evolves as the decrement of temperature will become an crucial problem for the heavy Weyl fermion phase, which may lead to new unique phenomena in these systems. Secondly, in heavy fermion systems, the energy scale of the quasiparticle bands is orders smaller than the ordinary semiconductor or semimetal systems, which makes it more sensitive to various of the external field, i.e. the pressure, mag-netic field and strain, providing large tunability to the distribution of the Weyl nodes. kx ky kz Γ Z N Σ X P (001) Surface (010) Surface (a) (b) FIG. 1. (Color online) Crystal structure and Brillouin zone (BZ). (a) The crystal symmetry of CeRu4Sn6...

show abstract

“…UPt 3 ) [13][14][15][16] or correlated magnetic semimetals [17] (e.g. SmB 6 [18] or CeRu 4 Sn 6 [19]). In particular, for unconventional superconductors, the nuclear quadrupole resonance (NQR) spin lattice relaxation provides information about N (E) around the E F and allows us to distinguish between point nodes (N (E) ∝ E 2 ) and line nodes (N (E) ∝ E).…”

mentioning

confidence: 99%

Emergent Weyl Fermion Excitations in TaP Explored byTa181Quadrupole Resonance

et al. 2017

Self Cite

View full text Add to dashboard Cite

The181 Ta quadrupole resonance (NQR) technique has been utilized to investigate the microscopic magnetic properties of the Weyl semi-metal TaP. We found three zero-field NQR signals associated with the transition between the quadrupole split levels for Ta with I=7/2 nuclear spin. A quadrupole coupling constant, νQ =19.250 MHz, and an asymmetric parameter of the electric field gradient, η = 0.423 were extracted, in good agreement with band structure calculations. In order to examine the magnetic excitations, the temperature dependence of the spin lattice relaxation rate (1/T1T ) has been measured for the f2-line (±5/2 ↔ ±3/2 transition). We found that there exists two regimes with quite different relaxation processes. Above T * ≈ 30 K, a pronounced (1/T1T ) ∝ T 2 behavior was found, which is attributed to the magnetic excitations at the Weyl nodes with temperature dependent orbital hyperfine coupling. Below T *, the relaxation is mainly governed by Korringa process with 1/T1T = constant, accompanied by an additional T −1/2 type dependence to fit our experimental data. We show that Ta-NQR is a novel probe for the bulk Weyl fermions and their excitations.PACS numbers: 02.40. Pc, 76.60.Gv, 31.30.Gs The past decade has seen an explosion of interest in the role of topology in condensed matter physics. Major discoveries have included the two dimensional graphene [1] and the topological insulators (TI) (e.g. HgTe or Bi 2 Se 3 ), [2][3][4] whose topological properties require the existence of gapless surface states. Many of the new materials host exotic excitations whose observation can be regarded as direct experimental evidence for the existence of quasiparticles. Arguably, the most topical of the new classes of materials are Dirac-and Weyl-semi metals which are predicted to host topologically protected states in the bulk. [5] In Dirac semimetals (DSM), [5][6][7] (e.g. Cd 2 As 3 or Na 3 Bi) each node contains fermions of two opposite chiralities, whereas in the Weyl semimetals (WSM), [8][9][10][11][12] an even more interesting situation arises. A combination of non-centrosymmetric crystal structure and sizable spin-orbit coupling (SOC) causes the nodes to split into pairs of opposite chirality (Weyl points). In the ideal case, there would be exactly half filling of the relevant bands, such that the Weyl points would sit at the Fermi level (E F ) and the Weyl fermions would be massless. In actuality, Weyl semimetals such as the d-electron monophosphides NbP and TaP, E F does not exactly coincide with the Weyl nodes. [9,10,12] However, if the nodes sit close enough to E F , in a region of linear dispersion (E ∝ k), the Weyl physics can still be observed in the excitations in the energy window k B T . A key issue in the study of the monophosphides is therefore to establish how close to the Fermi level the Weyl points sit, and to estimate the range of energy over which the linear dispersion exists. This presents a considerable experimental challenge. The nodes appear in the electronic structure of the bulk, and the mate...

show abstract

Low-temperature properties ofCeRu4Sn6from NMR and specific heat measurements: Heavy fermions emerging from a Kondo-insulating state

Cited by 28 publications

References 29 publications

Anisotropic Thermopower of the Kondo Insulator $$\hbox {CeRu}_4\hbox {Sn}_6$$ CeRu 4 Sn 6

Anisotropic Thermopower of the Kondo Insulator $$\hbox {CeRu}_4\hbox {Sn}_6$$ CeRu 4 Sn 6

Heavy Weyl Fermion State in CeRu4Sn6

Emergent Weyl Fermion Excitations in TaP Explored byTa181Quadrupole Resonance

Contact Info

Product

Resources

About