SUPERCONDUCTIVITY AND QUANTUM PHASE TRANSITIONS  IN WEAK ITINERANT FERROMAGNETS

It is argued that the phase transition in low Tc clean itinerant ferromagnets is generically of first order, due to correlation effects that lead to a nonanalytic term in the free energy. A tricritical point separates the line of first order transitions from Heisenberg critical behavior at higher temperatures. Sufficiently strong quenched disorder suppresses the first order transition via the appearance of a critical endpoint. A semi-quantitative discussion is given in terms of recent experiments on MnSi and UGe 2. It is then shown that the critical temperature for spin-triplet, p-wave superconductivity mediated by spin fluctuations is generically much higher in a Heisenberg ferromagnetic phase than in a paramagnetic one, due to the coupling of magnons to the longitudinal magnetic susceptibility. This qualitatively explains the phase diagram recently observed in UGe 2 and ZrZn 2.

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Fluctuation-Induced First-Order Transition and Tricritical Point in EuPtSi

Journal of the Physical Society of Japan ◽

10.7566/jpsj.88.093701 ◽

2019 ◽

Vol 88 (9) ◽

pp. 093701 ◽

Cited By ~ 6

Author(s):

Toshiro Sakakibara ◽

Shota Nakamura ◽

Shunichiro Kittaka ◽

Masashi Kakihana ◽

Masato Hedo ◽

...

Keyword(s):

Tricritical Point ◽

Order Transition ◽

First Order ◽

First Order Transition

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Absence of first-order transition and tricritical point in the dynamic phase diagram of a spatially extended bistable system in an oscillating field

Physical Review E ◽

10.1103/physreve.66.056127 ◽

2002 ◽

Vol 66 (5) ◽

Cited By ~ 101

Author(s):

G. Korniss ◽

P. A. Rikvold ◽

M. A. Novotny

Keyword(s):

Phase Diagram ◽

Tricritical Point ◽

Order Transition ◽

Bistable System ◽

First Order ◽

Dynamic Phase ◽

Spatially Extended ◽

First Order Transition

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SUPERCONDUCTIVITY NEAR POMERANCHUK INSTABILITIES IN THE SPIN CHANNEL

Modern Physics Letters B ◽

10.1142/s0217984913501029 ◽

2013 ◽

Vol 27 (14) ◽

pp. 1350102 ◽

Cited By ~ 3

Author(s):

DANIEL G. BARCI ◽

PAULO S. A. BONFIM

Keyword(s):

Cooper Pair ◽

Mean Field ◽

P Wave ◽

Strong Coupling Regime ◽

Coupling Constant ◽

Field Phase ◽

S Wave ◽

Spin Channel ◽

First Order ◽

First Order Transition

We study the competition between a Pomeranchuk instability in the spin channel with angular momentum ℓ = 1 and an attractive interaction, favoring Cooper-pair formation. We found that the superconducting gap strongly suppresses the phase space for the Pomeranchuk instability. We computed a mean-field phase diagram displaying a first order transition between two superconductor phases with different symmetries: p-wave (with spontaneously generated spin-orbit interaction) and s-wave for greater values of the coupling constant. Moreover, we have looked for a possible modulated superconducting phase. We have found that this phase appears only as a metastable state in the strong coupling regime.

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Tuning magnetic confinement of spin-triplet superconductivity

npj Quantum Materials ◽

10.1038/s41535-020-00270-w ◽

2020 ◽

Vol 5 (1) ◽

Author(s):

Wen-Chen Lin ◽

Daniel J. Campbell ◽

Sheng Ran ◽

I-Lin Liu ◽

Hyunsoo Kim ◽

...

Keyword(s):

Applied Pressure ◽

Upper Critical Field ◽

Magnetic Confinement ◽

Superconducting Phase ◽

Zero Field ◽

First Order ◽

Diode Oscillator ◽

Spin Triplet ◽

First Order Transition ◽

Tunnel Diode Oscillator

Abstract Electrical magnetoresistance and tunnel diode oscillator measurements were performed under external magnetic fields up to 41 T applied along the crystallographic b axis (hard axis) of UTe2 as a function of temperature and applied pressures up to 18.8 kbar. In this work, we track the field-induced first-order transition between superconducting and magnetic field-polarized phases as a function of applied pressure, showing suppression of the transition with increasing pressure until the demise of superconductivity near 16 kbar and the appearance of a pressure-induced ferromagnetic-like ground state that is distinct from the field-polarized phase and stable at zero field. Together with evidence for the evolution of a second superconducting phase and its upper critical field with pressure, we examine the confinement of superconductivity by two orthogonal magnetic phases and the implications for understanding the boundaries of triplet superconductivity.

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First-order transition features of the triangular Ising model with nearest- and next-nearest-neighbor antiferromagnetic interactions

Physica A Statistical Mechanics and its Applications ◽

10.1016/j.physa.2007.04.051 ◽

2007 ◽

Vol 383 (2) ◽

pp. 351-371 ◽

Cited By ~ 14

Author(s):

A. Malakis ◽

N.G. Fytas ◽

P. Kalozoumis

Keyword(s):

Ising Model ◽

Nearest Neighbor ◽

Order Transition ◽

First Order ◽

First Order Transition

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Chiral Waveguide Optomechanics: First Order Quantum Phase Transitions with Z3 Symmetry Breaking

Physical Review Letters ◽

10.1103/physrevlett.125.263606 ◽

2020 ◽

Vol 125 (26) ◽

Author(s):

D. D. Sedov ◽

V. K. Kozin ◽

I. V. Iorsh

Keyword(s):

Phase Transitions ◽

Symmetry Breaking ◽

Quantum Phase Transitions ◽

Quantum Phase ◽

First Order

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The Effect of Topology on Phase Behavior under Confinement

Processes ◽

10.3390/pr9071220 ◽

2021 ◽

Vol 9 (7) ◽

pp. 1220

Author(s):

Arnout M. P. Boelens ◽

Hamdi A. Tchelepi

Keyword(s):

Phase Behavior ◽

Density Functional ◽

Capillary Condensation ◽

Good Description ◽

Functional Theory ◽

Minkowski Functionals ◽

First Order ◽

Lennard Jones ◽

And Topology ◽

First Order Transition

This work studies how morphology (i.e., the shape of a structure) and topology (i.e., how different structures are connected) influence wall adsorption and capillary condensation under tight confinement. Numerical simulations based on classical density functional theory (cDFT) are run for a wide variety of geometries using both hard-sphere and Lennard-Jones fluids. These cDFT computations are compared to results obtained using the Minkowski functionals. It is found that the Minkowski functionals can provide a good description of the behavior of Lennard-Jones fluids down to small system sizes. In addition, through decomposition of the free energy, the Minkowski functionals provide a good framework to better understand what are the dominant contributions to the phase behavior of a system. Lastly, while studying the phase envelope shift as a function of the Minkowski functionals it is found that topology has a different effect depending on whether the phase transition under consideration is a continuous or a discrete (first-order) transition.

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