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Two-particle self-consistent approach for broken symmetry phases
by Lorenzo Del Re
Submission summary
| Authors (as registered SciPost users): | Lorenzo Del Re |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202407_00001v2 (pdf) |
| Date submitted: | 2024-09-11 17:39 |
| Submitted by: | Del Re, Lorenzo |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approaches: | Theoretical, Computational |
Abstract
Spontaneous symmetry breaking of interacting fermion systems constitutes a major challenge for many-body theory due to the proliferation of new independent scattering channels once absent or degenerate in the symmetric phase. One example is given by the ferro/antiferromagnetic broken symmetry phase (BSP) of the Hubbard model, where vertices in the spin-transverse and spin-longitudinal channels become independent with a consequent increase in the computational power for their calculation. Here we generalize the formalism of the non-perturbative Two-Particle-Self-Consistent method (TPSC) to treat broken SU(2) magnetic phases of the Hubbard model, providing with a efficient yet reliable method. We show that in the BSP, the sum-rule enforcement of susceptibilities must be accompanied by a modified gap equation resulting in a renormalisation of the order parameter, vertex corrections and the preservation of the gap-less feature of the Goldstone modes. We then apply the theory to the antiferromagnetic phase of the Hubbard model in the cubic lattice at half-filling. We compare our results of double occupancies and staggered magnetisation to the ones obtained using Diagrammatic Monte Carlo showing excellent quantitative agreement. We demonstrate how vertex corrections play a central role in lowering the Higgs resonance with respect to the quasi-particle excitation gap in the spin-longitudinal susceptibility, yielding a well visible Higgs-mode.
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
Author comments upon resubmission
Thank you for providing the referee reports. We are grateful to the referee for their careful, positive, and constructive feedback, which has helped us to restructure the paper and make it more accessible to a broader audience. Additionally, addressing the referee’s comments point by point allowed us to further clarify that our method extends beyond mean-field approaches and holds great potential for applications in the emerging field of altermagnetism.
Given the significant improvements we have made to fully address the referee’s requests, we believe that this revised version of our paper is now suitable for publication in SciPost Physics.
Best Regards
Lorenzo Del Re
List of changes
A diff file has been attached as a pdf file (please see Comment to the Resubmission).