Spin Fluctuations and Non-fermi Liquid Behavior Close to a Quantum Critical Point in CeNi2Ge2

Spin Fluctuations and Non-fermi Liquid Behavior Close to a Quantum Critical Point in CeNi2Ge2
Author: Bilal El Zoghbi
Publisher:
Total Pages: 184
Release: 2009
Genre: Critical point
ISBN:

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The physical properties of the heavy fermion compound CeNi2Ge2, have been investigated in this dissertation. Although heavy fermion systems are strongly correlated electron systems with hybridization of conduction and f-electrons, they usually still follow a Landau Fermi liquid description with high renormalized fermion masses. Modifying the electron correlations by chemical substitution or pressure, heavy fermions can be driven through a magnetic quantum critical point changing, e.g., from a magnetic ordered into a nonmagnetic ground state. Close to such a quantum critical point, Fermi liquid description breaks down and signs of "non-Fermi liquid" behavior appear. Signs for non-Fermi liquid properties are increased low energy excitations resulting in power laws when approaching lower temperatures as observed in the specific heat coefficient which is otherwise temperature independent in Fermi liquid, and in electric resistivity that displays exponents less than two. CeNi2Ge2 is one of the few heavy fermion compounds that shows these signs of non-Fermi liquid behavior without external pressure or chemical substitution. It has been suggested that non-Fermi liquid behavior is caused by quantum critical magnetic fluctuations close to an antiferromagnetic quantum critical point. In order to classify the nature of this non-Fermi liquid behavior, neutron scattering experiments were performed to find and characterize the relevant critical magnetic fluctuations. Several single crystals grown in collaboration with Leiden University and polycrystals grown in our lab have been studied. Beside the neutron scattering measurements performed on all available samples, we also carried out low temperature characterization measurements on part of these samples in dilution refrigerator and SQUID magnetometer. Electrical resistivity measurements have confirmed results reported by other researchers. Signs of non-Fermi liquid behavior below T=10K appear with the temperature dependence of electrical resistivity, DT~T^n, where

Thermal Transport in Strongly Correlated Rare-Earth Intermetallic Compounds

Thermal Transport in Strongly Correlated Rare-Earth Intermetallic Compounds
Author: Heike Pfau
Publisher: Springer
Total Pages: 133
Release: 2016-07-20
Genre: Technology & Engineering
ISBN: 3319395432

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This thesis explores thermal transport in selected rare-earth-based intermetallic compounds to answer questions of great current interest. It also sheds light on the interplay of Kondo physics and Fermi surface changes. By performing thermal conductivity and electrical resistivity measurements at temperatures as low as 25mK, the author demonstrates that the Wiedemann–Franz law, a cornerstone of metal physics, is violated at precisely the magnetic-field-induced quantum critical point of the heavy-fermion metal YbRh2Si2. This first-ever observation of a violation has dramatic consequences, as it implies a breakdown of the quasiparticle picture. Utilizing an innovative technique to measure low-temperature thermal transport isothermally as a function of the magnetic field, the thesis interprets specific, partly newly discovered, high-field transitions in CeRu2Si2 and YbRh2Si2 as Lifshitz transitions related to a change in the Fermi surface. Lastly, by applying this new technique to thermal conductivity measurements of the skutterudite superconductor LaPt4Ge12, the thesis proves that the system is a conventional superconductor with a single energy gap. Thus, it refutes the widespread speculations about unconventional Cooper pairing in this material.

Handbook of Magnetic Materials

Handbook of Magnetic Materials
Author: K.H.J. Buschow
Publisher: Elsevier
Total Pages: 447
Release: 2014-12-01
Genre: Science
ISBN: 0444635386

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Over the last few decades magnetism has seen an enormous expansion into a variety of different areas of research, notably the magnetism of several classes of novel materials that share with truly ferromagnetic materials only the presence of magnetic moments. Volume 23 of the Handbook of Magnetic Materials, like the preceding volumes, has a dual purpose. With contributions from leading authorities in the field, it includes a variety of self-contained introductions to a given area in the field of magnetism without requiring recourse to the published literature. It is also a reference for scientists active in magnetism research, providing readers with novel trends and achievements in magnetism. In each of these articles an extensive description is given in graphical as well as in tabular form, with much emphasis being placed on the discussion of the experimental material within the framework of physics, chemistry and material science. Comprises topical review articles written by leading authorities Introduces given topics in the field of magnetism Describes novel trends and achievements in magnetism

Physics, Uspekhi

Physics, Uspekhi
Author:
Publisher:
Total Pages: 462
Release: 2007
Genre: Physics
ISBN:

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Acta Physica Polonica

Acta Physica Polonica
Author:
Publisher:
Total Pages: 660
Release: 2003
Genre: Nuclear physics
ISBN:

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The Kondo Problem to Heavy Fermions

The Kondo Problem to Heavy Fermions
Author: Alexander Cyril Hewson
Publisher: Cambridge University Press
Total Pages: 476
Release: 1997-04-28
Genre: Science
ISBN: 9780521599474

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The behaviour of magnetic impurities in metals has posed problems to challenge the condensed matter theorist over the past 30 years. This book deals with the concepts and techniques which have been developed to meet this challenge, and with their application to the interpretation of experiments. This book will be of interest to condensed matter physicists, particularly those interested in strong correlation problems. The detailed discussions of advanced many-body techniques should make it of interest to theoretical physicists in general.

Holographic Quantum Matter

Holographic Quantum Matter
Author: Sean A. Hartnoll
Publisher: MIT Press
Total Pages: 407
Release: 2018-03-16
Genre: Science
ISBN: 0262348020

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A comprehensive overview of holographic methods in quantum matter, written by pioneers in the field. This book, written by pioneers in the field, offers a comprehensive overview of holographic methods in quantum matter. It covers influential developments in theoretical physics, making the key concepts accessible to researchers and students in both high energy and condensed matter physics. The book provides a unique combination of theoretical and historical context, technical results, extensive references to the literature, and exercises. It will give readers the ability to understand the important problems in the field, both those that have been solved and those that remain unsolved, and will enable them to engage directly with the current literature. The book describes a particular interface between condensed matter physics, gravitational physics, and string and quantum field theory made possible by holographic duality. The chapters cover such topics as the essential workings of the holographic correspondence; strongly interacting quantum matter at a fixed commensurate density; compressible quantum matter with a variable density; transport in quantum matter; the holographic description of symmetry broken phases; and the relevance of the topics covered to experimental challenges in specific quantum materials. Holographic Quantum Matter promises to be the definitive presentation of this material.

Photoelectron Spectroscopy

Photoelectron Spectroscopy
Author: Stefan Hüfner
Publisher: Springer Science & Business Media
Total Pages: 525
Release: 2013-11-11
Genre: Science
ISBN: 3662031507

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An up-to-date introduction to the field, treating in depth the electronic structures of atoms, molecules, solids and surfaces, together with brief descriptions of inverse photoemission, spin-polarized photoemission and photoelectron diffraction. Experimental aspects are considered throughout and the results carefully interpreted by theory. A wealth of measured data is presented in tabullar for easy use by experimentalists.