Pressure-induced Fermi-liquid behavior in the Kondo insulator<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">SmB</mml:mi></mml:mrow><mml:mrow><mml:mn>6</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mo>:</mml:mo></mml:math>Possible transition through a quantum critical point

Gabáni, S.; Bauer, E.; Berger, St.; Flachbart, К.; Paderno, Yu. B.; Paul, Ch.; Pavlı́k, V.; Shitsevalova, N.

doi:10.1103/physrevb.67.172406

Cited by 63 publications

(69 citation statements)

References 21 publications

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“…The fitting errors are 1.9% at 1 bar and 3.7% at 16.5 kbar, which are much smaller than change of 1/T 1 (around 20%) in the temperature range 20-100 K. The value of E g at 1 bar is in good agreement with other NMR experiments [1,10]. However, the decrease of E g with increasing applied pressure is quite large in comparison with other experimental methods [2,9]. One of the possible explanations is that pressure brings about not only the decrease of E g , but also changes in spin correlations.…”

Section: Methodssupporting

confidence: 76%

“…The properties of this system are governed by several energy scales. In temperature range from ≈ 70 K to 15 K the properties are characterized by hybridization gap E g ≈ 10-20 meV [2] and the system is semiconducting. Between 15 K and 5 K an in-gap band with activation energy E d ≈ 3-5 meV (situated below the conduction band) was observed by several experimental measurements [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

“…Below about 5 K the electrical conductivity is constant due to small conductivity channel in the E d band. Experiments under applied pressure show that the insulating gap closes at pressure ≈ 40 kbar and above ≈ 60 kbar long range magnetic order appears [2,9]. * corresponding author; e-mail: gabriel.pristas@saske.sk…”

Section: Introductionmentioning

confidence: 99%

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¹¹B-NMR Study of SmB₆under Pressure

et al. 2010

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We present first experimental results of 11 B-NMR of SmB 6 under applied pressure. From measurement of nuclear spin-lattice relaxation time (T 1 ) we find that with applied pressure the value of activation gap E g is decreasing. This decrease is larger than in case of other experimental techniques. We suppose that the enhancement of 1/T 1 in temperature range 20-100 K with applied pressure reflects not only a suppression of hybridization gap, but also changes in spin correlations.

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Section: Methodssupporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

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¹¹B-NMR Study of SmB₆under Pressure

et al. 2010

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“…However, the gap being caused by hybridization is discussed controversially. For instance, if the hybridization is altered by the application of pressure, a continuous change in the gap is expected (15,16), although other experiments show a discontinuous change (17,18). This is relevant because altered atomic distances at the surface (e.g., by valence changes at the surface) then also may result in a conducting surface layer.…”

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confidence: 99%

Hybridization gap and Fano resonance in SmB₆

Rößler¹,

Jang

Kim

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

127

160

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Hybridization between conduction electrons and the strongly interacting f-electrons in rare earth or actinide compounds may result in new states of matter. Depending on the exact location of the concomitant hybridization gap with respect to the Fermi energy, a heavy fermion or an insulating ground state ensues. To study this entanglement locally, we conducted scanning tunneling microscopy and spectroscopy (STS) measurements on the "Kondo insulator" SmB 6 . The vast majority of surface areas investigated were reconstructed, but infrequently, patches of varying sizes of nonreconstructed Smor B-terminated surfaces also were found. On the smallest patches, clear indications for the hybridization gap with logarithmic temperature dependence (as expected for a Kondo system) and for intermultiplet transitions were observed. On nonreconstructed surface areas large enough for coherent cotunneling, we were able to observe clear-cut Fano resonances. Our locally resolved STS indicated considerable finite conductance on all surfaces independent of their structure, not proving but leaving open the possibility of the existence of a topologically protected surface state.M aterials with strong electron correlations continue to draw enormous attention, not only because they may give rise to fundamentally new states of matter or new phenomena but also because of the hope for advanced technological applications. Heavy fermion (HF) materials, i.e., intermetallics of certain rare earths (REs), such as Ce, Sm, and Yb, are model systems to study strong electronic correlations (1). Here, the RE-derived localized 4f states are covalently mixed with the conduction-band states and, thus, acquire a finite lifetime. The associated decay rate in relation to the energy of the localized 4f state corresponds to the valency. In an Sm-based HF system, the valence lies between 3+ (4f 5 ) and 2+ (4f 6 ), which implies a considerable amount of charge fluctuations. This usually is referred to as intermediate valence (2). In addition to the abovementioned mixing of 4f states and the conduction band, which is well described within the framework of one-electron models, a manybody interaction is operating between the 4f and conduction electrons. This "Kondo effect" (3) eventually leads to a screening of the local moments as a result of particle-hole excitations that are manifested by a narrow Abrikosov-Suhl, or Kondo, resonance at E F , the width of which is given by the single-ion Kondo temperature T K .Because of the periodic arrangement of REs in an HF intermetallic, the Kondo resonances form a weakly dispersive HF or "coherent 4f−" band, resulting in a heavy Fermi liquid state well below T K . The band interaction between the renormalized 4f and the conduction band generates a so-called hybridization gap, which opens at around T K . Under certain conditions, E F may reside inside this gap, characterizing a so-called Kondo insulator (4).SmB 6 is such a Kondo insulator, with a valence ν ∼ 2:6 (5), ν being slightly temperature dependent (6, 7). A sharp de...

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“…CeIrSb [35]). Moreover, assuming that increasing pressure roughly corresponds to reducing the interaction strength, we can qualitatively account for the nonuniversal behavior of the gap as observed in several Kondo semiconductors [33,[36][37][38][39][40].Model and method. Our starting point is the topological Anderson lattice model on a square lattice, H =…”

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confidence: 99%

Many-body breakdown of indirect gap in topological Kondo insulators

Wysokiński

Fabrizio

2016

Phys. Rev. B

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We show that the inclusion of nonlocal correlation effects in a variational wave function for the ground state of a topological Anderson lattice Hamiltonian is capable of describing both topologically trivial insulating phases and nontrivial ones characterized by an indirect gap, as well as its closure at the transition into a metallic phase. The method, though applied to an oversimplified model, thus captures the metallic and insulating states that are indeed observed in a variety of Kondo semiconductors, while accounting for topologically nontrivial band structures. PACS numbers: 71.27.+a, 71.30.+h, 03.65.Vf Introduction. Phenomena at the crossroads of topological insulators and strongly correlated systems have recently gained a lot of attention, mainly stimulated by theoretical proposals that the inclusion of strong correlations in specific models with a nontrivial topological content may give rise to novel and interesting phenomena [1][2][3][4][5]. However, electronic correlations in most of the discovered topological insulators [6,7] seem to be relatively weak, and hence of minor importance. For that reason, the concept of topological Kondo insulators (TKIs) originally put forward in Refs.[8] and [9] is particularly appealing due to its possible realization in already known Kondo insulating compounds [10]. Notably, SmB 6 is convincingly confirmed to be a TKI [11][12][13][14][15][16][17][18][19] with strong evidence of the essential role played by many-body correlations [20,21].Theoretically, the main physical properties of TKI are frequently described in the framework of topological Anderson lattice models in which strong spin-orbit coupling is encoded into a spin-dependent hybridization with odd parity in momentum space [8,9,22]. Many-body correlations in these models have been mostly treated by the slave-boson approach or by the dynamical mean-field theory (DMFT), and predicted to induce quantum phase transitions between topologically distinct bulk insulating phases [22][23][24].The aim of this work is to demonstrate that accounting for nonlocal spatial correlations, beyond those already well captured by the mentioned techniques, plays an important role in modeling TKIs. Specifically, those nonlocal correlations supply the f electron self-energy with a momentum dependence, which is otherwise purely local within DMFT and at the saddle point of the slave-boson theory. Remarkably, such a momentum dependence allows one to describe, above a critical interaction strength, the emergence of a topological Kondo insulator with an indirect gap, and its subsequent closure at the transition into a metallic state, an intriguing result opposite to the conventional Mott phenomenon where increasing interaction instead favours the onset of an insulating state. We disclose this scenario in two dimensions by means of the diagrammatic expansion of the Gutzwiller wave function (GWF) technique [25,26]. CeIrSb [35]). Moreover, assuming that increasing pressure roughly corresponds to reducing the interaction strength, we can ...

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Pressure-induced Fermi-liquid behavior in the Kondo insulatorSmB6:Possible transition through a quantum critical point

Cited by 63 publications

References 21 publications

¹¹B-NMR Study of SmB₆under Pressure

¹¹B-NMR Study of SmB₆under Pressure

Hybridization gap and Fano resonance in SmB₆

Many-body breakdown of indirect gap in topological Kondo insulators

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Pressure-induced Fermi-liquid behavior in the Kondo insulatorSmB6:Possible transition through a quantum critical point

Cited by 63 publications

References 21 publications

11B-NMR Study of SmB6under Pressure

11B-NMR Study of SmB6under Pressure

Hybridization gap and Fano resonance in SmB6

Many-body breakdown of indirect gap in topological Kondo insulators

Contact Info

Product

Resources

About

¹¹B-NMR Study of SmB₆under Pressure

¹¹B-NMR Study of SmB₆under Pressure

Hybridization gap and Fano resonance in SmB₆