scholarly journals Novel excitations near quantum criticality in geometrically frustrated antiferromagnet CsFeCl3

2019 ◽  
Vol 5 (10) ◽  
pp. eaaw5639 ◽  
Author(s):  
Shohei Hayashida ◽  
Masashige Matsumoto ◽  
Masato Hagihala ◽  
Nobuyuki Kurita ◽  
Hidekazu Tanaka ◽  
...  
Keyword(s):  
Order Parameter ◽  
Critical Pressure ◽  
Quantum Critical Point ◽  
Single Mode ◽  
Wave Theory ◽  
Quantum Criticality ◽  
Geometrically Frustrated ◽  
Amplitude Fluctuations ◽  
Pressure Phase ◽  
Triangular Lattice Antiferromagnet

The investigation of materials that exhibit quantum phase transition provides valuable insights into fundamental problems in physics. We present neutron scattering under pressure in a triangular-lattice antiferromagnet that has a quantum disorder in the low-pressure phase and a noncollinear structure in the high-pressure phase. The neutron spectrum continuously evolves through critical pressure; a single mode in the disordered state becomes soft with the pressure and it splits into gapless and gapped modes in the ordered phase. Extended spin-wave theory reveals that the longitudinal and transverse fluctuations of spins are hybridized in the modes because of noncollinearity, and previously unidentified magnetic excitations are formed. We report a new hybridization of the phase and amplitude fluctuations of the order parameter near a quantum critical point in a spontaneously symmetry-broken state.

scholarly journals Computer-Aided Laser-Fiber Output Beam 3D Spatial and Angular Design

Symmetry ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 83
Author(s):  
Rocío Pérez de Prado ◽  
Sebastián García-Galán ◽  
José Enrique Muñoz-Expósito ◽  
Adam Marchewka
Keyword(s):  
Gaussian Beam ◽  
Beam Theory ◽  
Single Mode ◽  
Wave Theory ◽  
Spatial Behavior ◽  
Output Beam ◽  
Laser Fiber ◽  
Computer Aided ◽  
Fiber Output ◽  
Transverse Electromagnetic

Multiple laser beams and single-mode optical fibers output can be approximated by assuming that the emitted light has a symmetrical Gaussian intensity profile, which corresponds to the transverse electromagnetic mode (TEM00), which is designated as a Gaussian beam. Current free-accessible design tools are limited to the spatial analysis of the beams, in general, and to the intensity, in particular, and to the graphical visualization in 2D with very limited options. In this work, a novel a computer-aided laser-fiber output beam TEM00 designer, CATEM00, is presented based on the 3D representations typically provided by camera beam profilers, and on the fundamentals of the wave theory of light, including diverse flexibility capabilities for graphical manipulation and parameter comprehension both in terms of spatial behavior and in angular confinement. It must be highlighted that not only is the spatial limitation design of light impact relevant in TEM00 applications but, also, the angle with which the light reaches the target. Hence, the availability of capabilities of phase design in TEM00 following the paraxial limitations is highly convenient. Results and discussion in terms of intensity, power, divergence and wave fronts are presented considering a set of study cases, showing its coherence with Gaussian beam theory.

scholarly journals Order parameter fluctuations at a buried quantum critical point

2012 ◽  
Vol 109 (19) ◽  
pp. 7224-7229 ◽  
Author(s):  
Y. Feng ◽  
J. Wang ◽  
R. Jaramillo ◽  
J. van Wezel ◽  
S. Haravifard ◽  
...  
Keyword(s):  
Critical Point ◽  
Order Parameter ◽  
Quantum Critical Point ◽  
Quantum Critical

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 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.

scholarly journals Polyamorphism Mirrors Polymorphism in the Liquid–Liquid Transition of a Molecular Liquid

2020 ◽  
Author(s):  
Finlay Walton ◽  
John Bolling ◽  
Andrew Farrell ◽  
Jamie MacEwen ◽  
Christopher Syme ◽  
...  
Keyword(s):  
Order Parameter ◽  
Supercooled Liquid ◽  
Supercooled Liquids ◽  
Molecular Packing ◽  
Single Component ◽  
Triphenyl Phosphite ◽  
Amorphous Phases ◽  
Geometrically Frustrated ◽  
Intimate Connection ◽  
Liquid Transition

Liquid-liquid transitions between two amorphous phases in a single-component liquid (polyamorphism) have defied explanation and courted controversy. All known examples of liquid–liquid transitions have been observed in the supercooled liquid suggesting an intimate connection with vitrification and locally favored structures inhibiting crystallization. However, there is precious little information about the local molecular packing in supercooled liquids meaning that the order parameter of the transition is still unknown. Here, we investigate the liquid–liquid transition in triphenyl phosphite and show that it is caused by the competition between liquid structures that mirror two crystal polymorphs. The liquid–liquid transition is found to be between a geometrically frustrated liquid to a dynamically frustrated glass. These results indicate a general link between polymorphism and polyamorphism and will lead to a much greater understanding of the physical basis of liquid–liquid transitions and allow the discovery of other examples.

scholarly journals Bose polarons near quantum criticality

Science ◽  
2020 ◽  
Vol 368 (6487) ◽  
pp. 190-194 ◽  
Author(s):  
Zoe Z. Yan ◽  
Yiqi Ni ◽  
Carsten Robens ◽  
Martin W. Zwierlein
Keyword(s):  
Critical Temperature ◽  
Quantum Critical Point ◽  
Spectral Width ◽  
Quantum Criticality ◽  
Einstein Condensate ◽  
Resonant Interactions ◽  
Bose Einstein Condensate ◽  
Modern Physics ◽  
Quantum Critical ◽  
Bose Einstein

The emergence of quasiparticles in interacting matter represents one of the cornerstones of modern physics. However, in the vicinity of a quantum critical point, the existence of quasiparticles comes under question. Here, we created Bose polarons near quantum criticality by immersing atomic impurities in a Bose-Einstein condensate (BEC) with near-resonant interactions. Using radiofrequency spectroscopy, we probed the energy, spectral width, and short-range correlations of the impurities as a function of temperature. Far below the superfluid critical temperature, the impurities formed well-defined quasiparticles. Their inverse lifetime, given by their spectral width, increased linearly with temperature at the so-called Planckian scale, consistent with quantum critical behavior. Close to the BEC critical temperature, the spectral width exceeded the impurity’s binding energy, signaling a breakdown of the quasiparticle picture.

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