A METAMAGNETIC QUANTUM CRITICAL ENDPOINT IN Sr3Ru2O7

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3258-3264 ◽  
Author(s):  
S. A. GRIGERA ◽  
A. P. MACKENZIE ◽  
A. J. SCHOFIELD ◽  
S. R. JULIAN ◽  
G. G. LONZARICH
Keyword(s):  
Quantum Critical Point ◽  
Point Of View ◽  
Zero Temperature ◽  
Tuning Parameters ◽  
First Order ◽  
End Point ◽  
Fundamental Point ◽  
New Type ◽  
Quantum Critical ◽  
The Magnetic Field

In this paper, we discuss the concept of a metamagnetic quantum critical end-point, consequence of the depression to zero temperature of a critical end-point terminating a line of first order first transitions. This new type of quantum critical point (QCP) is interesting both from a fundamental point of view: a study of a symmetry conserving QCP, and because it opens the possibility of the use of symmetry breaking tuning parameters, notably the magnetic field. In addition, we discuss the experimental evidence for the existence of such a QCP in the bilayer ruthenate Sr3Ru2O7.

Higher-Order Multilevel Solvers for the EHL Line and Point Contact Problem

1994 ◽  
Vol 116 (4) ◽  
pp. 741-750 ◽  
Author(s):  
C. H. Venner
Keyword(s):  
Contact Problem ◽  
Computing Time ◽  
Point Contact ◽  
Higher Order ◽  
Second Order ◽  
Point Of View ◽  
First Order ◽  
Fundamental Point ◽  
Numerical Solver ◽  
Circular Contact

This paper addresses the development of efficient numerical solvers for EHL problems from a rather fundamental point of view. A work-accuracy exchange criterion is derived, that can be interpreted as setting a limit to the price paid in terms of computing time for a solution of a given accuracy. The criterion can serve as a guideline when reviewing or selecting a numerical solver and a discretization. Earlier developed multilevel solvers for the EHL line and circular contact problem are tested against this criterion. This test shows that, to satisfy the criterion a second-order accurate solver is needed for the point contact problem whereas the solver developed earlier used a first-order discretization. This situation arises more often in numerical analysis, i.e., a higher order discretization is desired when a lower order solver already exists. It is explained how in such a case the multigrid methodology provides an easy and straightforward way to obtain the desired higher order of approximation. This higher order is obtained at almost negligible extra work and without loss of stability. The approach was tested out by raising an existing first order multilevel solver for the EHL line contact problem to second order. Subsequently, it was used to obtain a second-order solver for the EHL circular contact problem. Results for both the line and circular contact problem are presented.

scholarly journals Magnetic field-driven quantum criticality in antiferromagnetic CePtIn4

2019 ◽  
Vol 116 (41) ◽  
pp. 20333-20338 ◽  
Author(s):  
Debarchan Das ◽  
Daniel Gnida ◽  
Piotr Wiśniewski ◽  
Dariusz Kaczorowski
Keyword(s):  
Magnetic Field ◽  
Tricritical Point ◽  
Condensed Matter ◽  
Quantum Critical Point ◽  
Quantum Criticality ◽  
Transition Line ◽  
First Order ◽  
Experimental Systems ◽  
Quantum Critical ◽  
Second Order Phase Transition

Physics of the quantum critical point is one of the most perplexing topics in current condensed-matter physics. Its conclusive understanding is forestalled by the scarcity of experimental systems displaying novel aspects of quantum criticality. We present comprehensive experimental evidence of a magnetic field-tuned tricritical point separating paramagnetic, antiferromagnetic, and metamagnetic phases in the compound CePtIn4. Analyzing field variations of its magnetic susceptibility, magnetoresistance, and specific heat at very low temperatures, we trace modifications of the antiferromagnetic structure of the compound. Upon applying a magnetic field of increasing strength, the system undergoes metamagnetic transitions which persist down to the lowest temperature investigated, exhibiting first-order–like boundaries separating magnetic phases. This yields a unique phase diagram where the second-order phase transition line terminates at a tricritical point followed by 2 first-order lines reaching quantum critical end points as T→ 0. Our findings demonstrate that CePtIn4 provides innovative perspective for studies of quantum criticality.

scholarly journals First-Order Superconducting Transition near a Ferromagnetic Quantum Critical Point

2003 ◽  
Vol 90 (7) ◽  
Author(s):  
Andrey V. Chubukov ◽  
Alexander M. Finkel’stein ◽  
Robert Haslinger ◽  
Dirk K. Morr
Keyword(s):  
Critical Point ◽  
Quantum Critical Point ◽  
Superconducting Transition ◽  
First Order ◽  
Quantum Critical

scholarly journals EFFECTS OF STRAIN COUPLING AND MARGINAL DIMENSIONALITY IN THE NATURE OF PHASE TRANSITION IN QUANTUM PARAELECTRICS

2013 ◽  
Vol 27 (08) ◽  
pp. 1350028 ◽  
Author(s):  
NABYENDU DAS
Keyword(s):  
Free Energy ◽  
Critical Point ◽  
Finite Temperature ◽  
Order Parameter ◽  
Quantum Critical Point ◽  
Order Transition ◽  
Zero Temperature ◽  
First Order ◽  
Quantum Paraelectrics ◽  
First Order Transition

Here a recently observed weak first order transition in doped SrTiO 3 [Taniguchi, Itoh and Yagi, Phys. Rev. Lett.99, 017602 (2007)] is argued to be a consequence of the coupling between strain and order parameter fluctuations. Starting with a semi-microscopic action, and using renormalization group equations for vertices, we write the free energy of such a system. This fluctuation renormalized free energy is then used to discuss the possibility of first order transition at zero temperature as well as at finite temperature. An asymptotic analysis predicts small but a finite discontinuity in the order parameter near a mean field quantum critical point at zero temperature. In case of finite temperature transition, near quantum critical point such a possibility is found to be extremely weak. Results are in accord with some experimental findings on quantum paraelectrics such as SrTiO 3 and KTaO 3.

NON-FERMI LIQUID BEHAVIOR IN THE SINGLE-IMPURITY MIXED VALENCE PROBLEM

1995 ◽  
Vol 09 (23) ◽  
pp. 1527-1533
Author(s):  
GUANG-MING ZHANG ◽  
ZHAO-BIN SU ◽  
LU YU
Keyword(s):  
Critical Point ◽  
Fermi Liquid ◽  
Mixed Valence ◽  
Quantum Critical Point ◽  
Coulomb Interactions ◽  
Single Impurity ◽  
Liquid Behavior ◽  
New Type ◽  
Quantum Critical ◽  
Fermi Liquid Behavior

An effective Hamiltonian of the Anderson single-impurity model with finite-range Coulomb interactions is derived near a particular limit, which is analogous to the Toulouse limit of the ordinary Kondo problem, and the physical properties around the mixed valence quantum critical point are calculated. At this quantum critical point, the local moment is only partially quenched and X-ray edge singularities are exhibited. Around this point, a new type of non-Fermi liquid behavior is predicted with an extra specific heat C imp ~ T1/4 + AT ln T and spin-susceptibility χ imp ~T−3/4 + B ln T.

scholarly journals Gradual suppression of antiferromagnetism in BaFe2(As1−xPx)2: Zero-temperature evidence for a quantum critical point

2012 ◽  
Vol 85 (18) ◽  
Author(s):  
Tetsuya Iye ◽  
Yusuke Nakai ◽  
Shunsaku Kitagawa ◽  
Kenji Ishida ◽  
Shigeru Kasahara ◽  
...  
Keyword(s):  
Critical Point ◽  
Quantum Critical Point ◽  
Zero Temperature ◽  
Quantum Critical

scholarly journals Critical end point in a thermomagnetic nonlocal NJL model

2017 ◽  
Vol 32 (26) ◽  
pp. 1750162 ◽  
Author(s):  
F. Márquez ◽  
R. Zamora
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Phase Diagram ◽  
Order Phase Transition ◽  
Chemical Potential ◽  
First Order ◽  
End Point ◽  
First Order Phase Transition ◽  
First Order Phase ◽  
The Magnetic Field

In this paper, we explore the critical end point in the [Formula: see text] phase diagram of a thermomagnetic nonlocal Nambu–Jona-Lasinio model in the weak field limit. We work with the Gaussian regulator, and find that a crossover takes place at [Formula: see text], [Formula: see text]. The crossover turns to a first-order phase transition as the chemical potential or the magnetic field increases. The critical end point of the phase diagram occurs at a higher temperature and lower chemical potential as the magnetic field increases. This result is in accordance to similar findings in other effective models. We also find that there is a critical magnetic field, for which a first-order phase transition takes place even at [Formula: see text].

scholarly journals Pressure-tuned quantum criticality in the antiferromagnetic Kondo semimetal CeNi2−δAs2

2015 ◽  
Vol 112 (44) ◽  
pp. 13520-13524 ◽  
Author(s):  
Yongkang Luo ◽  
F. Ronning ◽  
N. Wakeham ◽  
Xin Lu ◽  
Tuson Park ◽  
...  
Keyword(s):  
Electrical Transport ◽  
Carrier Density ◽  
Quantum Critical Point ◽  
Quantum Criticality ◽  
Kondo Lattice ◽  
Antiferromagnetic Order ◽  
Zero Temperature ◽  
Electrical Transport Properties ◽  
Continuous Transition ◽  
Quantum Critical

The easily tuned balance among competing interactions in Kondo-lattice metals allows access to a zero-temperature, continuous transition between magnetically ordered and disordered phases, a quantum-critical point (QCP). Indeed, these highly correlated electron materials are prototypes for discovering and exploring quantum-critical states. Theoretical models proposed to account for the strange thermodynamic and electrical transport properties that emerge around the QCP of a Kondo lattice assume the presence of an indefinitely large number of itinerant charge carriers. Here, we report a systematic transport and thermodynamic investigation of the Kondo-lattice system CeNi2−δAs2 (δ ≈ 0.28) as its antiferromagnetic order is tuned by pressure and magnetic field to zero-temperature boundaries. These experiments show that the very small but finite carrier density of ∼0.032 e−/formular unit in CeNi2−δAs2 leads to unexpected transport signatures of quantum criticality and the delayed development of a fully coherent Kondo-lattice state with decreasing temperature. The small carrier density and associated semimetallicity of this Kondo-lattice material favor an unconventional, local-moment type of quantum criticality and raises the specter of the Nozières exhaustion idea that an insufficient number of conduction-electron spins to separately screen local moments requires collective Kondo screening.

SUPERFLUID TO BOSE METAL TRANSITION IN SYSTEMS WITH RESONANT PAIRING

2008 ◽  
Vol 22 (25n26) ◽  
pp. 4379-4385
Author(s):  
JULIUS RANNINGER
Keyword(s):  
Critical Point ◽  
Exchange Coupling ◽  
Degrees Of Freedom ◽  
Fundamental Problem ◽  
Spatial Scales ◽  
Phase Locking ◽  
Quantum Critical Point ◽  
Zero Temperature ◽  
Pair Exchange ◽  
Quantum Critical

Experiments in thin films whose thickness can be modified and by this way induce a superconductor to insulator transition, seem to suggest that in the quantum critical regime of this phase transition there might be a Bose metal, i.e., uncondensed bosonic carriers with a finite dissipation. This poses a fundamental problem as to our understanding of how such a state could be justified. On the basis of a simple Boson-Fermion model, where bosonic and fermionic degrees of freedom are strongly inter-related via a Boson-Fermion pair exchange coupling g, we illustrate how such a bosonic metal phase could possibly come about. We show that, as we approach the quantum critical point at some critical gc from the superfluid side, the superfluid phase locking is sustained only for longer and longer spatial scales. On a finite spatial scale, the boson have a quasi-free itinerant behavior with metallic features. At the quantum critical point the systems exhibits a phase separation which shows a ressemblance to that of a He 3– He 4 mixture. This could be the clue to the apparent dilemma of a Bose metal at zero temperature.

Sign in / Sign up

Export Citation Format

Share Document