ANTIFERROMAGNETIC QUANTUM PHASE TRANSITION IN THE QUANTUM PSEUDOGAP PHASE OF CUPRATES

2001 ◽  
Vol 15 (09n10) ◽  
pp. 277-284
Author(s):  
HYOK-JON KWON
Keyword(s):  
Phase Transition ◽  
Quantum Phase Transition ◽  
Quantum Critical Point ◽  
Expansion Method ◽  
Quantum Phase ◽  
Ginzburg Landau ◽  
Large N ◽  
Insulating Phase ◽  
Néel Order ◽  
D Wave

We investigate a zero-temperature itinerant antiferromagnetic transition where the fermions possess a d-wave gap. This problem pertains to both the nodal liquid insulating phase and the d-wave superconducting phase of the underdoped cuprates. We find that a non-trivial quantum phase transition exists, and that the quantum critical point is dominated by a long-ranged interaction (|x-y|-2d) of the Néel order parameter, which is induced by the Dirac-like fermions near gap nodes. We formulate a Ginzburg–Landau functional and estimate the critical exponents via the large-n expansion method.

scholarly journals Quantum phase transition in a two-dimensional Kondo-Heisenberg model: A dynamical Schwinger-boson large- N approach

2020 ◽  
Vol 102 (11) ◽  
Author(s):  
Jiangfan Wang ◽  
Yung-Yeh Chang ◽  
Chung-Yu Mou ◽  
Stefan Kirchner ◽  
Chung-Hou Chung
Keyword(s):  
Phase Transition ◽  
Quantum Phase Transition ◽  
Heisenberg Model ◽  
Quantum Phase ◽  
Two Dimensional ◽  
Large N

scholarly journals Topological Frustration can modify the nature of a Quantum Phase Transition

2021 ◽  
Author(s):  
Vanja Marić ◽  
Gianpaolo Torre ◽  
Fabio Franchini ◽  
Salvatore Giampaolo
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Quantum Phase Transition ◽  
Landau Theory ◽  
Continuous Phase ◽  
Quantum Systems ◽  
Quantum Phase ◽  
Local Order ◽  
Ginzburg Landau ◽  
One Dimensional

Abstract Ginzburg-Landau theory of continuous phase transitions implicitly assumes that microscopic changes are negligible in determining the thermodynamic properties of the system. In this work we provide an example that clearly contrasts with this assumption. In particular, we consider the 2-cluster-Ising model, a one-dimensional spin-1/2 system that is known to exhibit a quantum phase transition between a magnetic and a nematic phase. By imposing boundary conditions that induce topological frustration we show that local order is completely destroyed on both sides of the transition and that the two thermodynamic phases can only be characterized by string order parameters. Having proved that topological frustration is capable of altering the nature of a system's phase transition, this result is a clear challenge to current theories of phase transitions in complex quantum systems.

scholarly journals Continuous N\'{e}el-VBS quantum phase transition in non-local one-dimensional systems with SO(3) symmetry

2021 ◽  
Vol 10 (2) ◽  
Author(s):  
Chao-Ming Jian ◽  
Yichen Xu ◽  
Xiao-Chuan Wu ◽  
Cenke Xu
Keyword(s):  
Phase Transition ◽  
Quantum Phase Transition ◽  
Quantum Critical Point ◽  
Valence Bond ◽  
Spin Symmetry ◽  
Quantum Phase ◽  
Edge States ◽  
One Dimensional ◽  
Nonlocal Interactions ◽  
Quantum Critical

One dimensional (1d) interacting systems with local Hamiltonians can be studied with various well-developed analytical methods. Recently novel 1d physics was found numerically in systems with either spatially nonlocal interactions, or at the 1d boundary of 2d quantum critical points, and the critical fluctuation in the bulk also yields effective nonlocal interactions at the boundary. This work studies the edge states at the 1d boundary of 2d strongly interacting symmetry protected topological (SPT) states, when the bulk is driven to a disorder-order phase transition. We will take the 2d Affleck-Kennedy-Lieb-Tasaki (AKLT) state as an example, which is a SPT state protected by the SO(3) spin symmetry and spatial translation. We found that the original (1+1)d boundary conformal field theory of the AKLT state is unstable due to coupling to the boundary avatar of the bulk quantum critical fluctuations. When the bulk is fixed at the quantum critical point, within the accuracy of our expansion method, we find that by tuning one parameter at the boundary, there is a generic direct transition between the long range antiferromagnetic Néel order and the valence bond solid (VBS) order. This transition is very similar to the Néel-VBS transition recently found in numerical simulation of a spin-1/2 chain with nonlocal spatial interactions. Connections between our analytical studies and recent numerical results concerning the edge states of the 2d AKLT-like state at a bulk quantum phase transition will also be discussed.

scholarly journals Adiabatic quenches and characterization of amplitude excitations in a continuous quantum phase transition

2016 ◽  
Vol 113 (34) ◽  
pp. 9475-9479 ◽  
Author(s):  
Thai M. Hoang ◽  
Hebbe M. Bharath ◽  
Matthew J. Boguslawski ◽  
Martin Anquez ◽  
Bryce A. Robbins ◽  
...  
Keyword(s):  
Phase Transition ◽  
Quantum Phase Transition ◽  
Energy Gap ◽  
Quantum Critical Point ◽  
Mean Field ◽  
Finite Size ◽  
Quantum Phase ◽  
Nonequilibrium Dynamics ◽  
Many Body ◽  
Goldstone Modes

Spontaneous symmetry breaking occurs in a physical system whenever the ground state does not share the symmetry of the underlying theory, e.g., the Hamiltonian. This mechanism gives rise to massless Nambu–Goldstone modes and massive Anderson–Higgs modes. These modes provide a fundamental understanding of matter in the Universe and appear as collective phase or amplitude excitations of an order parameter in a many-body system. The amplitude excitation plays a crucial role in determining the critical exponents governing universal nonequilibrium dynamics in the Kibble–Zurek mechanism (KZM). Here, we characterize the amplitude excitations in a spin-1 condensate and measure the energy gap for different phases of the quantum phase transition. At the quantum critical point of the transition, finite-size effects lead to a nonzero gap. Our measurements are consistent with this prediction, and furthermore, we demonstrate an adiabatic quench through the phase transition, which is forbidden at the mean field level. This work paves the way toward generating entanglement through an adiabatic phase transition.

scholarly journals Reply to “Comment on ‘Quantum phase transition in the four-spin exchange antiferromagnet’ ”

2010 ◽  
Vol 82 (13) ◽  
Author(s):  
Valeri N. Kotov ◽  
D. X. Yao ◽  
A. H. Castro Neto ◽  
D. K. Campbell
Keyword(s):  
Phase Transition ◽  
Quantum Phase Transition ◽  
Spin Exchange ◽  
Quantum Phase
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