Dynamics and transport properties of Kondo insulators

Vidhyadhiraja, N. S.; Smith, Victoria Ellen; Logan, David E.; Krishnamurthy, H. R.

doi:10.1088/0953-8984/15/24/301

Cited by 46 publications

(158 citation statements)

References 63 publications

(334 reference statements)

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“…In the strongly correlated HF regime, physical properties such as ρ mag (T ) exhibit scaling as a function of T /ω L , independent of the interaction U and hybridization V as detailed in I; occurring formally for all T /ω L in the asymptotic strong coupling limit, and in material practice over a significant albeit naturally finite T /ω L range as seen above for CeB 6 (and in [15] for Kondo insulators). This is not by contrast the case in the IV regime, and neither is it to be expected.…”

Section: Y Balmentioning

confidence: 82%

Optical and transport properties of heavy fermions: theory compared to experiment

Vidhyadhiraja¹,

Logan²

2005

J. Phys.: Condens. Matter

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Abstract.Employing a local moment approach to the periodic Anderson model within the framework of dynamical mean-field theory, direct comparison is made between theory and experiment for the d.c. transport and optical conductivities of paramagnetic heavy fermion and intermediate valence metals. Four materials, exhibiting a diverse range of behaviour in their transport/optics, are analysed in detail: CeB 6 , Y bAl 3 , CeAl 3 and CeCoIn 5 . Good agreement between theory and experiment is in general found, even quantitatively, and a mutually consistent picture of transport and optics results.

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Section: Y Balmentioning

confidence: 82%

Optical and transport properties of heavy fermions: theory compared to experiment

Vidhyadhiraja¹,

Logan²

2005

J. Phys.: Condens. Matter

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“…Complementary to the work of other authors 33,34,41,44,45,46 , which focus the rigorous techniques of many-body theory directly toward the underlying Hamiltonian, we will use a simplified approach based on effective low energy (near-E F ) PAM dispersion relations 43,47 . These dispersion relations (ǫ + and ǫ − in Figure 7) provide the basis for a simple unifying picture in which much of the low energy phenomenology of heavy fermion materials can be viewed, including the mass enhancement, aspects of magnetism, and transport measurements 48,49 .…”

Section: Modeling Pam Dispersionmentioning

confidence: 99%

Infrared dynamics ofYbIn1−xAgxCu4: Kondo scaling, sum rules, and temperature dependence

et al. 2006

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We present an infrared/optical study of the dynamics of the strongly correlated electron system YbIn1−xAgxCu4 as a function of doping and temperature for x ranging from 0 to 1, and T between 20 and 300 K. This study reveals information about the unusual phase transition as well as the phases themselves. Scaling relations emerge from the data and are investigated in detail using a periodic Anderson model based calculation. We also provide a picture in which to view both the low and high-energy x -dependent features of the infrared data, including identification of high energy, temperature dependent features.When exploring the complex terrain of correlated electron phases, one is often interested in the phase boundaries separating systems which are controlled by different physics. In the low doping regime (x<0.2) of YbIn 1−x Ag x Cu 4 , a temperature-driven, first-order electronic phase transition separates two phases which are characterized by widely disparate effective energy scales (T K ) associated with the effects of hybridization between the localized Yb f -electrons and the itinerant conduction electrons. This rapid change provides both an opportunity to identify and isolate features associated with many-body hybridization physics and raises fundamental questions regarding the origin of the transition itself.The valence transition in YbInCu 4 has been examined with a variety of experimental techniques 1,2,3,4,5,6,7 , and exhibits some similarities 8,9,10 to phase transitions observed in certain rare-earth intermetallic compounds 11,12 . Samples of high quality can be made, and provide the only known example of a valence transition occurring at ambient pressure in a stoichiometric sample. The synthesis of high quality single crystal samples has allowed the detailed study of the phase diagram of YbIn 1−x Ag x Cu 4 , and continued effort has revealed a tendency of the system to order ferromagnetically as the phase transition temperature is driven to zero either by pressure 13,14 or Y doping 13,15 . The presence of interesting phase competition in a system where the sample chemistry is well controlled enhances our interest in this correlated electron system. Figure 1 shows a schematic representation of the phase diagram of YbIn 1−x Ag x Cu 4 . At low doping, a line of first order phase transitions separates a low temperature, mixed-valent phase and a high temperature local moment phase. In YbInCu 4 (x=0) at high temperature (T > T v = 42 K), the magnetic response exhibits a Curie-Weiss form with magnitude appropriate to j = 7/2 moment of Yb and a small Weiss temperature 16 Θ W ∼ −13 K, which constrains the effective Kondo temperature appropriate in this high temperature range to be comparably small in magnitude. The resistivity in this temperature range 2 is very high for a metal (ρ dc ≃ 150µΩ-cm) and together with Hall measurements indicate a very low (hole) carrier concentration 2 . Lowering the temperature through the first order phase transition has dramatic effects on both the spin and charge response. For...

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“…We have quantified the penetration of disorder effects in these interfaces through the spectral weight difference function (equation (29). The spectral weight difference is maximum in the disordered Kondo insulator and decays algebraically with distance from the disordered Kondo insulator layer.…”

Section: Discussionmentioning

confidence: 99%

“…The symmetry broken at the mean-field level is restored by imposing adiabatic continuity to the non-interacting limit, and this step leads to the emergence of a Kondo scale. The details of the LMA for the single impurity Anderson model and the PAM may be found in references [29][30][31][32] . The extension to finite disorder may be found in Ref.…”

Section: Model and Methodsmentioning

confidence: 99%

Spectral changes in layeredf-electron systems induced by Kondo hole substitution in the boundary layer

et al. 2015

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We investigate the effect of disorder on the dynamical spectrum of layered f -electron systems. With random dilution of f -sites in a single Kondo insulating layer, we explore the range and extent to which Kondo hole incoherence can penetrate into adjacent layers. We consider three cases of neighboring layers: band insulator, Kondo insulator and simple metal. The disorder-induced spectral weight transfer, used here for quantification of the proximity effect, decays algebraically with distance from the boundary layer. Further, we show that the spectral weight transfer is highly dependent on the frequency range considered as well as the presence of interactions in the clean adjacent layers. The changes in the low frequency spectrum are very similar when the adjacent layers are either metallic or Kondo insulating, and hence are independent of interactions. In stark contrast, a distinct picture emerges for the spectral weight transfers across large energy scales. The spectral weight transfer over all energy scales is much higher when the adjacent layers are non-interacting as compared to when they are strongly interacting Kondo insulators. Thus, over all scales, interactions screen the disorder effects significantly. We discuss the possibility of a crossover from non-Fermi liquid to Fermi liquid behavior upon increasing the ratio of clean to disordered layers in particle-hole asymmetric systems.

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Dynamics and transport properties of Kondo insulators

Cited by 46 publications

References 63 publications

Optical and transport properties of heavy fermions: theory compared to experiment

Optical and transport properties of heavy fermions: theory compared to experiment

Infrared dynamics ofYbIn1−xAgxCu4: Kondo scaling, sum rules, and temperature dependence

Spectral changes in layeredf-electron systems induced by Kondo hole substitution in the boundary layer

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