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Special Transition and Extraordinary Phase on the Surface of a Two-Dimensional Quantum Heisenberg Antiferromagnet

by Chengxiang Ding, Wenjing Zhu, Wenan Guo, Long Zhang

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Submission summary

Authors (as registered SciPost users): Chengxiang Ding
Submission information
Preprint Link: scipost_202211_00001v3  (pdf)
Date accepted: 2023-05-22
Date submitted: 2023-05-05 05:22
Submitted by: Ding, Chengxiang
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
Specialties:
  • Condensed Matter Physics - Theory
  • Condensed Matter Physics - Computational
  • Statistical and Soft Matter Physics
Approach: Computational

Abstract

Continuous phase transitions exhibit richer critical phenomena on the surface than in the bulk, because distinct surface universality classes can be realized at the same bulk critical point by tuning the surface interactions. The exploration of surface critical behavior provides a window looking into higher-dimensional boundary conformal field theories. In this work, we study the surface critical behavior of a two-dimensional (2D) quantum critical Heisenberg model by tuning the surface coupling strength, and discover a direct special transition on the surface from the ordinary phase into an extraordinary phase. The extraordinary phase has a long-range antiferromagnetic order on the surface, in sharp contrast to the logarithmic decaying spin correlations in the 3D classical O(3) model. The special transition point has a new set of critical exponents, $y_{s}=0.86(4)$ and $\eta_{\parallel}=-0.33(1)$, which are distinct from the special transition of the classical O(3) model and indicate a new surface universality class of the 3D O(3) Wilson-Fisher theory.

List of changes

1. We fixed a typo: should growth -> should grow.

2. We further revise the discussion part according to the suggestion of Referee-2, i.e.,

we replace:

“In Ref. [17], the extraordinary-log phase was proposed based on the perturbative RG analysis near the normal fixed point at the 1D boundary. Starting from the normal fixed point, where the spins show an infinitesimal long-range order, the spin interactions would be relevant and lead to short-range correlations at a free-standing boundary, but the coupling with the bulk critical modes reverses the RG flow direction and makes the normal fixed point stable.”

by

“In Ref. [17], the extraordinary-log phase was proposed based on the perturbative RG analysis near the ordered fixed point at the 1D boundary. Starting from the ordered fixed point, spin fluctuations would lead to short-range correlations for a free-standing boundary, but the coupling with the bulk critical modes reverses the RG flow direction and makes the ordered fixed point stable.”

3. As to the question of the citation of Ref. 22: As pointed out by the referee-2, this reference does not exactly prove the existence of the boundary of the AF order; however, in the RG analysis, it does show the possibility of such boundary AF order; therefore, we added words like “possible”, “possibility”, or “may” to somewhere the place Ref. 22 is cited to keep the rigor of the statement.

Published as SciPost Phys. 15, 012 (2023)

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