arXiv subjects

Yi-Xiang Wang

Publications and source records attributed to Yi-Xiang Wang.

24 records · Page 2Linked to original sources

arXiv2020

Spontaneous symmetry breaking of an interacting Chern insulator on a topological square lattice

The interplay between topology and correlation lies at the forefront of modern condensed matter physics. In this paper, we study the extended fermion-Hubbard model, including the on-site as well as the nearest-neighbor repulsive interactions, on a topological square lattice that supports the Chern insulator. Within the mean-field method, we find that the spontaneous symmetry breaking (SSB) charge-density wave or antiferromagnetic insulator dominates the system when the onsite or nearest-neighbor interactions are strong enough. It is interesting that the antiferromagnetic Chern insulator will appear in the phase diagram when there is an explicitly nonvanishing sublattice potential. In addition, we explore how a finite-size ribbon structure affects the phase diagram and point out that the critical interaction for SSB occurs with weaker strength than the bulk system.

cond-mat.str-el↗

arXiv2020

Emergence of asymmetric fermionic order in interacting birefringent fermions

The birefringent fermions possess a spectrum with two distinct Fermi velocities. Here based on the lattice model, we use the mean-field method to investigate the interaction-induced phase transitions of the birefringent fermions. We consider both the short-range nearest-neighbor (NN) and next-nearest-neighbor (NNN) repulsive interactions and calculate the phase diagrams under different conditions. We find that the NN interactions can induce the asymmetric charge density wave order, while the NNN interactions can drive the asymmetric quantum anomalous Hall order (AQAH) in the large limit of anisotropy in the hopping integrals, β\rightarrow 1. The AQAH order is characterized by the unequal loop currents connecting the NNN sites and by the appearance of a gap between the two conduction (valence) bands. Such asymmetric fermionic orders can be attributed to the specific lattice geometry of the birefringent fermions. The implications of our results for experiments are also discussed.

cond-mat.str-el↗

arXiv2020

Repulsive Fermi gases in a two-dimensional lattice with non-Abelian gauge fields

Motivated by the recent experiment realizing bidirectional spin-orbit-coupled Bose-Einstein condensates (BEC), we theoretically explore the properties of repulsive fermions in the two-dimensional (2D) optical lattice with such non-Abelian gauge fields. Within the mean-field level, we find a novel phase of topological antiferromagnetic (TAFM) order which incorporates both the non-trivial topology due to spin-flip hopping and spontaneous symmetry breaking (SSB) for the in-plane spin order. We argue that the appearance of such a phase is generic for repulsive fermions in Chern bands achieved through spin-orbit coupling. Our work paves the way for further studies of fermionic generalization of 2D non-Abelian spin-orbit-coupled quantum gases.

cond-mat.str-el↗

arXiv2016

Improved liver T1rho measurement precision with a breathhold black blood single shot fast spin echo acquisition: a validation study in healthy volunteers

Purpose: To explore the usability and normal T1rho value of liver parenchyma with a novel single breathhold black blood single shot fast spin echo acquisition based liver imaging sequence. Materials and Methods: In total 19 health subjects (10 males, 9 females; mean age: 37.4 yrs; range: 23-54 yrs) participated in the study. 11 subjects had liver scanned twice in the same session to access scan-rescan repeatability. 12 subjects had liver scanned twice in two sessions with 7-10 days' interval to access scan-rescan reproducibility. MR was performed with a 3.0 T scanner with dual transmitter. The MR sequence allows simultaneous acquisition of 4 spin lock times (TSLs: 0ms, 10 ms, 30 ms, 50ms) in 10 second. Inherent black blood effect of fast spin echo and double inversion recovery were utilized to achieve blood signal suppression. Results: The technique demonstrated good image quality and minimal artifacts. For liver parenchyma, Bland-Altman plot showed the scan-rescan repeatability mean difference was 0.025 ms (95% limits of agreement: -1.163 to 1.213 ms), and intraclass correlation coefficient (ICC) was 0.977. The scan-rescan reproducibility mean difference was -0.075 ms (95% limits of agreement: -3.280 to 3.310 ms), and ICC was 0.820 which is better than the ICC of 0.764 of a previous bright blood multi-breath hold gradient echo acquisition technique. The liver T1rho value was 39.9 +/- 2.4 ms (range: 36.1 - 44.2 ms), which is lower than the value of 42.8=/-2.1 ms acquired with the previous bright blood technique. Conclusion: This study validated the application of a single breathhold black blood single shot fast spin echo acquisition based for human liver T1rho imaging. The lower liver parenchyma T1rho value and higher scan rescan reproducibility may improve of the sensitivity of this technique.

q-bio.TO↗

arXiv2016

Lumbar degenerative spondylolisthesis epidemiology: a systemic review with a focus on gender-specific and age-specific prevalence

The epidemiology of lumbar degenerative spondylolisthesis (DS) remains controversial. We performed a systemic review with the aim to have a better understanding of DS's prevalence in general population. The results showed the prevalence of DS is very gender specific and age specific. Both women and men have few DS before 50 years old, after 50 years old both women and men start to develop DS, with women having a faster developing rate than men. For elderly Chinese (>=65 yrs, mean age: 72.5 yrs), large population based studies (MsOS(Hong Kong) and MrOS (Hong Kong), females n=2000 and males n=2000) showed DS prevalence was for 25.0% for women and 19.1% for men, and the prevalence F:M (women:men) ratio was 1.3:1. The published data (MsOS(USA) and MrOS(USA) studies) seem to show elderly Caucasian American has a higher DS prevalence, being approximately 60-70% higher than elderly Chinese; however the prevalence F:M ratio was similar to elderly Chinese population. Patient data showed female patients more often received treatment than men; and preliminary data show the ratio of numbers of female patients received treatment compared with men did not differ between Northeast Asians (Chinese, Japanese, and Korean) and European and American Caucasians, being around 2:1 in elderly population. The existing data also suggest that menopause may be a contributing factor for the accelerated DS development in post-menopausal

q-bio.TO↗

arXiv2016

Edge states and phase diagram for graphene under polarized light

We investigate the topological phase transitions in graphene under the modulation of circularly polarized light, by analyzing the changes of edge states and its topological structures. A full phase diagram, with up to ten different topological phases, is presented in the parameter space spanned by the driving frequency and light strength. We find that the high-Chern number behavior is very common in the driven system. While the one-photon resonance can create the chiral edge states in the $π-$gap, the two-photon resonance will induce the counter-propagating edge modes in the zero-energy gap. When the driving light strength is strong, the number and even the chirality of the edge states may change in the $π-$gap. The robustness of the edge states to disorder potential are also examined. We close by discussing the feasibility of experimental proposals.

cond-mat.mes-hall↗