A Study of Strongly Correlated Electron Behavior in the Filled Skutterudites PDF Download
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Author: William M. Yuhasz
Publisher:
ISBN:
Category :
Languages : en
Pages : 146
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Book Description
In the search for new and interesting strongly correlated electron phenomena, a detailed study has been underway of the rare earth-based filled skutterudite compounds. This work has been driven by the rich variety of strongly correlated electron phenomena exhibited by the filled skutterudites such as metal insulator transitions, heavy fermion behavior, quadrupole ordering, non-Fermi liquid behavior, and heavy fermion superconductivity. The filled skutterudite compounds have the chemical formula MT4X12 where M = alkali metal, alkaline-earth, lanthanide, or actinide; T = Fe, Ru, or Os; and X = P, As, or Sb. To improve the general understanding of these systems and to look for other strongly correlated electron behavior, single crystals of Pr0.87Fe4Sb12, PrOs4As12, \PrOs4P12, SmOs4Sb12, and NdOs4Sb12 were grown and characterized with X-ray diffraction, magnetization, electrical resistivity and specific heat measurements. Measurements of the filled skutterudite compound Pr0.87Fe4Sb12 reveal long rang magnetic ordering below 4.1 K with indications of ferrimagnetic ordering. Features in the magnetization of the filled skutterudite PrOs4As12 are consistent with antiferromagnetic ordering below 2.3 K. The specific heat, electrical resistivity, and magnetization measurements on PrOs4As12 also show features consistent with at least 2 to 3 ordered phases. Strong crystalline electric field effects were observed in PrOs4P12 and SmOs4Sb12, with both systems exhibiting Schottky anomalies in specific heat measurements. Magnetic ordering was observed in SmOs4Sb12 below 2.6 K with a ferromagnetic component as indicated by hysteresis in the magnetization as a function of field at 2 K. Magnetic ordering was also observed in the filled skutterudite compound NdOs4Sb12 below 0.9 K. Analysis of the specific heat measurements on Pr0.87Fe4Sb12, PrOs4As12, SmOs4Sb12, and NdOs4Sb12 reveal an enhanced electron effective mass, with SmOs4Sb12 showing the largest enhancement.
Author: William M. Yuhasz
Publisher:
ISBN:
Category :
Languages : en
Pages : 146
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Book Description
In the search for new and interesting strongly correlated electron phenomena, a detailed study has been underway of the rare earth-based filled skutterudite compounds. This work has been driven by the rich variety of strongly correlated electron phenomena exhibited by the filled skutterudites such as metal insulator transitions, heavy fermion behavior, quadrupole ordering, non-Fermi liquid behavior, and heavy fermion superconductivity. The filled skutterudite compounds have the chemical formula MT4X12 where M = alkali metal, alkaline-earth, lanthanide, or actinide; T = Fe, Ru, or Os; and X = P, As, or Sb. To improve the general understanding of these systems and to look for other strongly correlated electron behavior, single crystals of Pr0.87Fe4Sb12, PrOs4As12, \PrOs4P12, SmOs4Sb12, and NdOs4Sb12 were grown and characterized with X-ray diffraction, magnetization, electrical resistivity and specific heat measurements. Measurements of the filled skutterudite compound Pr0.87Fe4Sb12 reveal long rang magnetic ordering below 4.1 K with indications of ferrimagnetic ordering. Features in the magnetization of the filled skutterudite PrOs4As12 are consistent with antiferromagnetic ordering below 2.3 K. The specific heat, electrical resistivity, and magnetization measurements on PrOs4As12 also show features consistent with at least 2 to 3 ordered phases. Strong crystalline electric field effects were observed in PrOs4P12 and SmOs4Sb12, with both systems exhibiting Schottky anomalies in specific heat measurements. Magnetic ordering was observed in SmOs4Sb12 below 2.6 K with a ferromagnetic component as indicated by hysteresis in the magnetization as a function of field at 2 K. Magnetic ordering was also observed in the filled skutterudite compound NdOs4Sb12 below 0.9 K. Analysis of the specific heat measurements on Pr0.87Fe4Sb12, PrOs4As12, SmOs4Sb12, and NdOs4Sb12 reveal an enhanced electron effective mass, with SmOs4Sb12 showing the largest enhancement.
Author: Columbine Corder Robinson
Publisher:
ISBN:
Category :
Languages : en
Pages : 122
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Author: Sergey Kravchenko
Publisher: CRC Press
ISBN: 9814745383
Category : Science
Languages : en
Pages : 244
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Book Description
The properties of strongly correlated electrons confined in two dimensions are a forefront area of modern condensed matter physics. In the past two or three decades, strongly correlated electron systems have garnered a great deal of scientific interest due to their unique and often unpredictable behavior. Two of many examples are the metallic state and the metal–insulator transition discovered in 2D semiconductors: phenomena that cannot occur in noninteracting systems. Tremendous efforts have been made, in both theory and experiment, to create an adequate understanding of the situation; however, a consensus has still not been reached. Strongly Correlated Electrons in Two Dimensions compiles and details cutting-edge research in experimental and theoretical physics of strongly correlated electron systems by leading scientists in the field. The book covers recent theoretical work exploring the quantum criticality of Mott and Wigner–Mott transitions, experiments on the metal–insulator transition and related phenomena in clean and dilute systems, the effect of spin and isospin degrees of freedom on low-temperature transport in two dimensions, electron transport near the 2D Mott transition, experimentally observed temperature and magnetic field dependencies of resistivity in silicon-based systems with different levels of disorder, and microscopic theory of the interacting electrons in two dimensions. Edited by Sergey Kravchenko, a prominent experimentalist, this book will appeal to advanced graduate-level students and researchers specializing in condensed matter physics, nanophysics, and low-temperature physics, especially those involved in the science of strong correlations, 2D semiconductors, and conductor–insulator transitions.
Author: Eric Dietzgen Bauer
Publisher:
ISBN:
Category :
Languages : en
Pages : 288
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Author: Ram Bahadur Adhikari
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Strongly correlated electron systems constitute a rich reservoir for interesting physical phenomena. The competition and interplay between the localized magnetic moments in partially filled d or f electron systems and the itinerant conduction electrons states lead to novel phenomena such as complex magnetic properties, unconventional superconductivity, non-Fermi-liquid behavior, and the coexistence of superconductivity and magnetism. Such intriguing physical phenomena can be achieved by tuning the system with a control parameter, such as chemical composition, applied pressure, and magnetic field. It is interesting to study the chemical substitution effects on the correlated f electron system along with magnetic field to explore their complex phase diagram. This dissertation work focuses on experimental studies of the Ce and Eu substituted filled skutterudite system PrPt4Ge12 over a wide range of doping, magnetic field, and temperature using heat capacity measurements. The first study will focus on the specific heat and electrical resistivity measurements performed on the Pr[subscript 1-x]Ce[subscript x]Pt4Ge12 crystals. We have found that Ce monotonically suppresses the superconducting transition temperature T[subscript c] and a small Ce concentration of x = 0.14 brings the T[subscript c] to as low as 0.6 K. We further have demonstrate that small Ce substitution does not affect the multiband nature of superconductivity seen previously in the parent compound PrPt4Ge12. On the other hand, our data provide evidence that one of the two gaps is nodal in the parent compound and that Ce substitution gradually suppresses the value of the nodal gap. To understand the possible interplay between superconductivity and magnetism, we study the same parent system PrPt4Ge12, this time substituting Pr with europium. The compound so formed is Pr[subscript 1-x]Eu[subscript x]Pt4Ge12 whose end members are superconductor (x = 0) and antiferromagnetic (x = 1) at lower temperatures, so that there is the possibility of interaction between superconductivity and magnetism in the intermediate doping range. The increase of Eu concentration leads to a suppression of the superconducting transition temperature as in the case of cerium substitution. There is a low temperature heat capacity anomaly present over the whole doping range. Our analysis of the heat capacity data shows that in alloys with x = 0.5 the Schottky peaks in the heat capacity in the superconducting state appear to be due to Zeeman splitting by an internal magnetic field. Our theoretical analysis suggests that this internal magnetic field is a result of short-range antiferromagnetic correlations between the europium ions. We further investigated the effect of Eu substitution on the Pr site through heat capacity measurements on the same system in an applied magnetic field. The low temperature heat capacity peaks seen in the samples with x
Author: David Sénéchal
Publisher: Springer Science & Business Media
ISBN: 0387008950
Category : Science
Languages : en
Pages : 370
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Book Description
Focusing on the purely theoretical aspects of strongly correlated electrons, this volume brings together a variety of approaches to models of the Hubbard type – i.e., problems where both localized and delocalized elements are present in low dimensions. The chapters are arranged in three parts. The first part deals with two of the most widely used numerical methods in strongly correlated electrons, the density matrix renormalization group and the quantum Monte Carlo method. The second part covers Lagrangian, Functional Integral, Renormalization Group, Conformal, and Bosonization methods that can be applied to one-dimensional or weakly coupled chains. The third part considers functional derivatives, mean-field, self-consistent methods, slave-bosons, and extensions. Taken together, the contributions to this volume represent a comprehensive overview of current problems and developments.
Author: Adolfo Avella
Publisher: American Institute of Physics
ISBN: 9780735403406
Category : Science
Languages : en
Pages : 322
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Book Description
This book contains lectures on strongly correlated electron systems presented by eminent physicists. These lectures are up-to-date summaries of relevant subjects in the field of condensed matter physics intended to train students. Contributions include: Strongly correlated electron behaviors and heavy Fermions in anomalous rare-earth and actinide systems; strong correlations in low dimensional systems; functional renormalization group approach to correlated electron systems; and numerical approaches to coupled quantum systems.
Author: V Emery
Publisher: World Scientific
ISBN: 9814553697
Category :
Languages : en
Pages : 364
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Book Description
The study of the correlated motion of electrons in solids is of increasing importance in condensed matter physics. In the past few years, the discovery of high-temperature superconductors has stimulated an enormous theoretical effort in this area, building on earlier theories of heavy-fermion and organic superconductors, and magnetic insulators. In a separate development the discovery of the fractional quantum Hall effect stimulated research into the behavior of the two-dimensional electron gas in a strong transverse magnetic field.The lectures at this school gave a systematic presentation of the current status of the theory in these areas. They covered the fractional quantum Hall effect and the many-body physics of the Hubbard model and its extensions, paying particular attention to the properties of doped insulators which are relevant for high-temperature superconductivity. There were detailed discussions of situations for which controlled calculations may be carried out — specifically infinite dimensions, one dimension, and generalized models in which the fermions have N components and N → •.
Author: Baskaran G
Publisher: World Scientific
ISBN: 9814513318
Category :
Languages : en
Pages : 506
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Author: Adolfo Avella
Publisher: American Institute of Physics
ISBN:
Category : Mathematics
Languages : en
Pages : 272
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Book Description
The papers were peer reviewed by a local panel. The objective of the meeting was to promote the progress of young scientists by means of training through research. The lectures are up-to-date monographs of relevant subjects in the field of condensed matter physics. Contributions include the following lectures: Electron-Phonon Interaction and Strong Correlations in High-Temperature Superconductors: One cannot avoid the unavoidable (The properties of the normal state and pairing mechanism in high-Tc superconductors, Forward scattering peak in the EPI, The FSP theory, The ARPES non-shift puzzle, Interesting predictions of the FSP theory); Strongly Correlated Electron Materials: Dynamical Mean-Field Theory and Electronic Structure (The basic principles of dynamical mean-field theory (DMFT), application of DMFT to the Mott transition, compare to recent spectroscopy, transport experiments; the key role of the quasiparticle coherence scale, transfers of spectral weight between low- and intermediate or high energies is emphasized); Monte Carlo Simulations of Quantum Systems with Global Updates (a model for doped antiferromagnets, first application of the hybrid loop algorithm, namely the t-Jmodel with 1/r2 interaction).
