SciPost Submission Page
Spin-1/2 XX chains with modulated Gamma interaction
by Mohammad Abbasi, Saeed Mahdavifar, Mostafa Motamedifar
Submission summary
| Authors (as registered SciPost users): | Saeed Mahdavifar |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202408_00019v1 (pdf) |
| Date submitted: | 2024-08-18 21:00 |
| Submitted by: | Mahdavifar, Saeed |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Theoretical |
Abstract
We study the spin-1/2 XX chain with a modulated Gamma interaction (GI), which results from the superposition of uniform and staggered Gamma terms. We diagonalize the Hamiltonian of the model exactly using the Fermionization technique. We then probe the energy gap and identify the gapped and gapless regions. We also examine the staggered chiral, staggered nematic and dimer order parameters to determine the different phases of the ground state phase diagram with their respective long-range orders. Our findings indicate that the model undergoes first-order, second-order, gapless-gapless, and gapped-gapped phase transitions.
Author indications on fulfilling journal expectations
- Provide a novel and synergetic link between different research areas.
- Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
- Detail a groundbreaking theoretical/experimental/computational discovery
- Present a breakthrough on a previously-identified and long-standing research stumbling block
Current status:
Reports on this Submission
Report
The spin-1/2 XX chain with modulated $\Gamma$ interaction can be mapped to free fermions via the Jordan-Wigner transformation. It can thus be solved exactly and the ground-state phase diagram be determined analytically. This is performed in great detail in the present work via several different observables and a rich phase diagram is revealed.
Apart from more formal issues, I was wondering how the sign change in the staggered chiral order parameter at $\alpha=\pm1$ is related to a topological phase transition (or any phase transition at all). In fact, I understand topology to be related to global properties of the system and thus not being detectable by a local observable such as the staggered chiral order parameter. I believe that this is a recurrent issue throughout the manuscript.
In any case, the model under investigation is a very specific model that is tailored to be exactly soluble. In particular, it is one-dimensional, whereas materials such as $\alpha$-RuCl$_3$ that are mentioned for motivation are probably best approximated by a two-dimensional model. I thus do not think that the Acceptance criteria of SciPost Physics are satisfied (see https://scipost.org/SciPostPhys/about#criteria). Nevertheless, a suitably revised version might be suitable for publication in SciPost Physics Core (see https://scipost.org/SciPostPhysCore/about#criteria for the corresponding Acceptance criteria).
Requested changes
1- Page 2: $\alpha$-RuCl$_3$ is misprinted.
2- Figure 1 is referenced at the end of Section 1, but not really discussed. I feel that it would be appropriate to add such a discussion.
3- The asymptotic behavior close to $\Gamma_1=0$ in Fig. 2(c) looks linear to me, i.e., I am unable to see the supposed exponent $\nu=3/2$. Please provide evidence, correct, or remove the corresponding statement on page 6.
4- Clarify meaning of sign change of the staggered chiral order parameter (e.g., in the discussion of Fig. 3(b) at the bottom of page 8, but also at other relevant places).
Recommendation
Accept in alternative Journal (see Report)