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Troć, R.; Samsel‐Czekała, M.; Stȩpień‐Damm, J.; Coqblin, B.

doi:10.1103/physrevb.85.224434

Cited by 12 publications

(4 citation statements)

References 56 publications

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“…A two‐band model (TBM) was extensively used to analyze the dominant contribution to TEP in the intermediate valence systems caused by scattering between a narrow f‐band and conduction‐band electrons as proposed by Gottwick et al . The role of full width at half‐maximum (FWHM) and peak position of the 4f‐density of states (DOS) with respect to the Fermi level are more important to understand the TEP of intermetallic compounds .…”

Section: Introductionmentioning

confidence: 99%

Enhancement in thermoelectric power of Ce(Ni_1−xCu_x)₂Al₃: An implication of two‐band conduction

Yadam

Singh

Venkateshwarlu

et al. 2014

Physica Status Solidi (b)

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The thermoelectric power (TEP), resistivity, and heat capacity of the polycrystalline Ce(Ni 1Àx Cu x ) 2 Al 3 system, for x ¼ 0.0-0.4, are reported. A clear enhancement of TEP at low temperatures is seen upon substitution of Cu and is expected to be useful for low-temperature thermoelectric applications. To understand such an enhanced TEP we have employed a twoband model based on the Ce-4f and conduction bands proposed by Gottwick et al. A clear evolution of a 4f band moving toward the Fermi level that is becoming sharpened is seen and is predicted to be close to resonance. The fit parameters of the TEP (S) are physically reasonable. The resistivity data shows an evolution from a simple compensated metal to a paramagnetic one via the Kondo route. This is in line with TEP parameters. In addition, a clear enhancement seen in the electronic part of the heat capacity upon Cu substitution and the evolution of magnetoresistance behavior corroborates the results. Possible bipolar effects are also taken into consideration along with an electron-phonon interaction term to explain the almost temperature-independent part of the resistivity, still yielding a considerable component of disorder.

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Section: Introductionmentioning

confidence: 99%

Enhancement in thermoelectric power of Ce(Ni_1−xCu_x)₂Al₃: An implication of two‐band conduction

Yadam

Singh

Venkateshwarlu

et al. 2014

Physica Status Solidi (b)

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“…The knowledge of the Fermi surface (FS) topology is crucial to understand the electron properties of quantum systems . The FS can be determined experimentally with various methods.…”

Section: Introductionmentioning

confidence: 99%

Electron–positron momentum densities in crystalline solids

Kontrym‐Sznajd

Sormann

2013

Physica Status Solidi (b)

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The uniqueness of information contained in electron densities r(p) in the extended momentum space is pointed out, showing that certain electronic properties can be derived only from r(p), directly related to the electron Bloch wave functions. The influence of many-body effects on the electron-positron (e-p) momentum density and of the crystal lattice periodicity on scattering effects is discussed. On the example of Mg it is illustrated that for simple metals there is a unique opportunity to estimate, for e-p densities, electron-electron correlation effects quantitatively.1 Introduction The knowledge of the Fermi surface (FS) topology is crucial to understand the electron properties of quantum systems [1][2][3][4]. The FS can be determined experimentally with various methods. The most common quantum oscillatory techniques [5][6][7] allow estimation of only some quantities related to FS without a visualization of its shape. Other techniques such as Compton scattering [8,9], angular correlation of annihilation radiation (ACAR) [10,11], and angle-resolved photoemission spectroscopy (ARPES) [12] yield information on the shape of FS in the whole reciprocal space [13]. The most direct method of probing electronic structure is ARPES, also known as ARUPS (angleresolved ultraviolet photoemission spectroscopy) [14,15]. As for each method, it has also some limitations [16], such as, e.g., those appearing in studies of small elliptical FS hole pockets in hydrated sodium cobalt oxides. These pockets were seen in Shubnikov-de Haas oscillations [17], phonon softening [18] and Compton scattering experiments [19] but not in ARPES measurements [20].ACAR experiments probe the momentum density of electron-positron (e-p) pairs in the extended momentum (p) space [11,13]

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“…While most cerium compounds show AFM order, some are ferromagnetic (FM): CeRu 2 Ge 2 [16], CeIn 2 [17,18], and CeRu 2 Al 2 B [19]. A number of uranium and neptunium heavy-fermion materials are also FM: UTe [20], UCu 0.9 Sb 2 [21], UCo 0.5 Sb 2 [22], NpNiSi 2 [23], Np 2 PdGa 3 [24], and UCu 2 Si 2 [25]. In addition, there are strong indications of robust coexistence of the Kondo effect and ferromagnetism, in particular in U compounds.…”

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confidence: 99%

“…In Refs. [25][26][27][28][29] it has been proposed that an appropriate minimal model for this behavior is the spin-1 version of the KLM, where in the mean-field picture the conduction-band electrons underscreen the local moments, while the residual moments order ferromagnetically. FM order appears for low and moderate electron filling n in the conduction band, n 0.5 [26,[30][31][32][33].…”

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confidence: 99%

Lifshitz phase transitions in the ferromagnetic regime of the Kondo lattice model

Golež

Žitko

2013

Phys. Rev. B

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We establish the low-temperature phase diagrams of the spin-1/2 and spin-1 Kondo lattice models as a function of the conduction-band filling n and the exchange coupling strength J in the regime of ferromagnetic effective exchange interactions (n 0.5). We show that both models have several distinct ferromagnetic phases separated by continuous Lifshitz transitions of the Fermi-pocket vanishing or emergence type: one of the phases has a true gap in the minority band (half metal), the others only a pseudogap. They can be experimentally distinguished by their magnetization curves; only the gapped phase exhibits magnetization rigidity. We find that, quite generically, ferromagnetism and Kondo screening coexist rather than compete, both in spin-1/2 and spin-1 models. We compute the Curie temperatures and establish a "ferromagnetic Doniach diagram" for both models. PACS numbers: 71.27.+a, 72.15.Qm, 75.20.Hr, 75.30.Kz, 75.30.Mb Materials with competing interactions, such as many lanthanide and actinide compounds, have complex lowtemperature phase diagrams with different ground states [1][2][3][4][5][6]. The Kondo lattice model (KLM) [7-9] describes a conduction band of itinerant electrons and a lattice of local moments on f shells, coupled at each site by an antiferromagnetic exchange interaction J. For large J, the moments are screened. The resulting paramagnetic state has Fermi liquid properties with strongly renormalized parameters. For small J, the conduction-band electrons are carriers of longrange magnetic interactions and the moments order. The two regimes are separated by a quantum phase transition at critical J * , as described by the Doniach diagram [10]. The Néel temperature increases at first quadratically with J, but then it peaks and decreases to zero at J * as the Kondo screening takes over. The simplest version of the KLM with spin-1/2 moments indeed has an antiferromagnetic (AFM) ground state (Néel order) for small J near half-filling [11,12]. The nature of the phase transition at J * has been investigated using a variety of methods, the most accurate of which confirm that the transition is second order (quantum critical) and indicate that it involves a change of the Fermi surface topology [13][14][15]. In the spin-1 KLM, there is no phase transition at half-filling and the AFM phase extends to large values of J. While most cerium compounds show AFM order, some are ferromagnetic (FM): CeRu 2 Ge 2 [16], CeIn 2 [17, 18], and CeRu 2 Al 2 B [19]. A number of uranium and neptunium heavy-fermion materials are also FM: UTe [20], UCu 0.9 Sb 2 [21], UCo 0.5 Sb 2 [22], NpNiSi 2 [23], Np 2 PdGa 3 [24], and UCu 2 Si 2 [25]. In addition, there are strong indications of robust coexistence of the Kondo effect and ferromagnetism, in particular in U compounds. In Refs. [25 -29] it has been proposed that an appropriate minimal model for this behavior is the spin-1 version of the KLM, where in the mean-field picture the conduction-band electrons underscreen the local moments, while the residual moments order ferromagnet...

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Interplay between ferromagnetism, SDW order, and underscreened Kondo lattice in UCu2Si2

Cited by 12 publications

References 56 publications

Enhancement in thermoelectric power of Ce(Ni_1−xCu_x)₂Al₃: An implication of two‐band conduction

Enhancement in thermoelectric power of Ce(Ni_1−xCu_x)₂Al₃: An implication of two‐band conduction

Electron–positron momentum densities in crystalline solids

Lifshitz phase transitions in the ferromagnetic regime of the Kondo lattice model

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Interplay between ferromagnetism, SDW order, and underscreened Kondo lattice in UCu2Si2

Cited by 12 publications

References 56 publications

Enhancement in thermoelectric power of Ce(Ni1−xCux)2Al3: An implication of two‐band conduction

Enhancement in thermoelectric power of Ce(Ni1−xCux)2Al3: An implication of two‐band conduction

Electron–positron momentum densities in crystalline solids

Lifshitz phase transitions in the ferromagnetic regime of the Kondo lattice model

Contact Info

Product

Resources

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Enhancement in thermoelectric power of Ce(Ni_1−xCu_x)₂Al₃: An implication of two‐band conduction

Enhancement in thermoelectric power of Ce(Ni_1−xCu_x)₂Al₃: An implication of two‐band conduction