A.M. Goldman
- Published in print:
- 2012
- Published Online:
- September 2012
- ISBN:
- 9780199592593
- eISBN:
- 9780191741050
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199592593.003.0011
- Subject:
- Physics, Theoretical, Computational, and Statistical Physics
Superconductor-insulator (SI) transitions of homogeneously disordered ultrathin quench-condensed films in many instances appear to be direct, without any intervening metallic regime. This is in ...
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Superconductor-insulator (SI) transitions of homogeneously disordered ultrathin quench-condensed films in many instances appear to be direct, without any intervening metallic regime. This is in contrast with what has been found in some other systems. These direct transitions have been analyzed using finite size scaling. The products of the dynamical critical exponent and the coherence length exponent found vary, depending upon the tuning parameter. They are approximately 1.3 for the thickness tuned SI transition, and approximately 0.7 for perpendicular and parallel magnetic field tuning. Charge tuning also yields 0.7. Assuming that the dynamical critical exponent is unity as is anticipated for systems with long range interactions, all of the transitions, except the thickness-tuned transition would appear to belong to the 3D XY universality class. This behavior is different from that observed for magnetic field tuned transitions of compounds such as InOx or TiN, or other metallic systems. The source of these differences is not known but may be due to differences in carrier density or structural or chemical disorder on a mesoscopic scale.Less
Superconductor-insulator (SI) transitions of homogeneously disordered ultrathin quench-condensed films in many instances appear to be direct, without any intervening metallic regime. This is in contrast with what has been found in some other systems. These direct transitions have been analyzed using finite size scaling. The products of the dynamical critical exponent and the coherence length exponent found vary, depending upon the tuning parameter. They are approximately 1.3 for the thickness tuned SI transition, and approximately 0.7 for perpendicular and parallel magnetic field tuning. Charge tuning also yields 0.7. Assuming that the dynamical critical exponent is unity as is anticipated for systems with long range interactions, all of the transitions, except the thickness-tuned transition would appear to belong to the 3D XY universality class. This behavior is different from that observed for magnetic field tuned transitions of compounds such as InOx or TiN, or other metallic systems. The source of these differences is not known but may be due to differences in carrier density or structural or chemical disorder on a mesoscopic scale.
Alexander Punnoose and Alexander M. Finkel’stein
- Published in print:
- 2012
- Published Online:
- September 2012
- ISBN:
- 9780199592593
- eISBN:
- 9780191741050
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199592593.003.0004
- Subject:
- Physics, Theoretical, Computational, and Statistical Physics
This chapter reviews here the two-parameter scaling theory of the dirty Fermi-liquid. The chapter shows that this theory captures both quantitatively (for small disorder) and qualitatively (for large ...
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This chapter reviews here the two-parameter scaling theory of the dirty Fermi-liquid. The chapter shows that this theory captures both quantitatively (for small disorder) and qualitatively (for large disorder) the physics of the Metal-Insulator Transition observed in two-dimensional electron systems.Less
This chapter reviews here the two-parameter scaling theory of the dirty Fermi-liquid. The chapter shows that this theory captures both quantitatively (for small disorder) and qualitatively (for large disorder) the physics of the Metal-Insulator Transition observed in two-dimensional electron systems.
A.V. Narlikar
- Published in print:
- 2014
- Published Online:
- June 2014
- ISBN:
- 9780199584116
- eISBN:
- 9780191747496
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199584116.003.0013
- Subject:
- Physics, Condensed Matter Physics / Materials
This chapter describes advances made with a variety of heavy fermion (HF) superconducting systems, adding new challenges to the physics of this growing field. Much of the understanding has evolved ...
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This chapter describes advances made with a variety of heavy fermion (HF) superconducting systems, adding new challenges to the physics of this growing field. Much of the understanding has evolved through a new class of phase transition, the quantum phase transition (QPT), occurring at a quantum critical point (QCP). Studies of QCPs have led to the realisation of complicated phase diagrams for various f-electron systems and, above all, an unconventional superconductivity. Various special features described include non-centrosymmetric materials, occurrence of multiple superconducting phases, FFLO state, hidden order and metamagnetic transitions. Similarly, the observation of exceptionally high Tc values in recently discovered Pu-based HF superconductors indicates that the field is wide open for unexpected developments resulting from the discovery of new systems. The phenomenon shows extreme sensitivity to defects, impurities and stoichiometry, and materials processing therefore poses a clear challenge to the discovery of new unconventional superconductors.Less
This chapter describes advances made with a variety of heavy fermion (HF) superconducting systems, adding new challenges to the physics of this growing field. Much of the understanding has evolved through a new class of phase transition, the quantum phase transition (QPT), occurring at a quantum critical point (QCP). Studies of QCPs have led to the realisation of complicated phase diagrams for various f-electron systems and, above all, an unconventional superconductivity. Various special features described include non-centrosymmetric materials, occurrence of multiple superconducting phases, FFLO state, hidden order and metamagnetic transitions. Similarly, the observation of exceptionally high Tc values in recently discovered Pu-based HF superconductors indicates that the field is wide open for unexpected developments resulting from the discovery of new systems. The phenomenon shows extreme sensitivity to defects, impurities and stoichiometry, and materials processing therefore poses a clear challenge to the discovery of new unconventional superconductors.
J. F. Scott
- Published in print:
- 2020
- Published Online:
- October 2020
- ISBN:
- 9780198862499
- eISBN:
- 9780191895319
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198862499.003.0008
- Subject:
- Physics, Condensed Matter Physics / Materials, Theoretical, Computational, and Statistical Physics
This chapter outlines how ferroelectric domain patterns link to various, cross-disciplinary, fundamental instabilities. It starts by highlighting the startling resemblance between Turing patterns and ...
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This chapter outlines how ferroelectric domain patterns link to various, cross-disciplinary, fundamental instabilities. It starts by highlighting the startling resemblance between Turing patterns and the ‘labyrinthine’ polar nanoregHions associated with ferroelectric relaxors. The chapter goes on to look at patterns arising out of the Landau-Ginzburg approach and links these to experimentally observed domain patterns. The link between Turing patterns and those from Landau-Ginzburg is particularly noteworthy as the terms, and considerations, of the two approaches differ: yet both can describe ferroic domain configurations in lead based ferroelectrics in different boundary conditions. This chapter considers other fundamental situations, such as Zhabotinskii-Belousov patterns and Richtmyer-Meshkov instabilities, before looking at the evolution of these patterns with increasing. It concludes by looking at the dimensionality of PbTiO3. Because many of these processes require diffusion, they should be absent (or qualitatively different) near Quantum Critical points.Less
This chapter outlines how ferroelectric domain patterns link to various, cross-disciplinary, fundamental instabilities. It starts by highlighting the startling resemblance between Turing patterns and the ‘labyrinthine’ polar nanoregHions associated with ferroelectric relaxors. The chapter goes on to look at patterns arising out of the Landau-Ginzburg approach and links these to experimentally observed domain patterns. The link between Turing patterns and those from Landau-Ginzburg is particularly noteworthy as the terms, and considerations, of the two approaches differ: yet both can describe ferroic domain configurations in lead based ferroelectrics in different boundary conditions. This chapter considers other fundamental situations, such as Zhabotinskii-Belousov patterns and Richtmyer-Meshkov instabilities, before looking at the evolution of these patterns with increasing. It concludes by looking at the dimensionality of PbTiO3. Because many of these processes require diffusion, they should be absent (or qualitatively different) near Quantum Critical points.