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Jia-Cheng He

Publications and source records attributed to Jia-Cheng He.

4 recordsLinked to original sources

The odd-parity altermagnetism induced reconstruction of the Chern-insulating phase in Haldane-Hubbard model

Odd-parity altermagnetism(ALM) extends compensated collinear magnetism beyond the even-parity spin splitting of conventional altermagnets, but its role in correlated topological phases remains largely unexplored. Using the cluster slave-spin method, we show that the odd-parity ALM appearing in the ALM Chern-insulating phase of Haldane-Hubbard model significantly reconstructs the local topology in the conventional Chern-insulating phase, while the total Chern number remains unchanged compared to the Chern-insulating phase. The Berry curvature becomes spin and valley selective; zigzag ribbons develop chiral-symmetry-breaking edge states; while armchair ribbons remain inversion symmetric. The optical response mirrors this separation between the local reconstruction and the global topology: low-energy spectra are governed by quasiparticles near the gap, whereas the low-frequency Hall conductivity stays quantized, $\sigma_{\rm T\uparrow}(\Omega\to 0)=\sigma_{\rm T\downarrow}(\Omega\to 0)=e^2/h$. These results establish the Haldane-Hubbard model as a minimal correlated platform for odd-parity altermagnetic topology.

cond-mat.str-el

Six-component pairing instability in the SU(4) $t$-$J$ chain

We use the density matrix renormalization group (DMRG) method to study the SU(4) $t$-$J$ chain. We find that, in addition to the conventional repulsive Luttinger liquid phase and phase separation, there are two phases in the attractive Luttinger liquid region dependent on whether the flavor gap is opened or not. The first with the flavor gap is the molecular superfluid phase (the SU(4) singlet instability) which is well-known in the attractive SU(4) Hubbard model ($U<0$). The second without the flavor gap is the superconducting phase (the six-component pairing instability). Furthermore, the molecular superfluid instability cannot coexist with the superconducting instability. This is general in SU($N$) models with $N>2$ and is well demonstrated by the theoretical analysis based on the phenomenological bosonization results.

cond-mat.str-el

Evidence of triplet superconductivity in Bi/Ni bilayers: Theoretical analysis of point contact Andreev reflection spectroscopy results

A theoretical formalism of Andreev reflection is employed to provide theoretical support for distinguishing between the singlet pairing and the triplet pairing by the point contact Andreev reflection (PCAR) experiments. We utilize our theoretical curves to fit the data of the PCAR experiment on unconventional superconductivity in the Bi/Ni bilayer [arXiv:1810.10403] and find the Anderson-Brinkman-Morel (ABM) state satisfies the main characteristics of the experimental data. The chiral cross-section of the ABM state might explain well the broken time-reversal symmetry determined by the polar Kerr effect measurements and the time-domain THz spectroscopy in Bi/Ni bilayers. Moreover, the Andreev reflection spectra of the Balian-Werthamer state and the chiral $p$-wave state are also presented.

cond-mat.supr-con

Gutzwiller approximation approach to the SU(4) $t$-$J$ model

We develop the Gutzwiller approximation method to obtain the renormalized Hamiltonian of the SU(4) $t$-$J$ model with the corresponding renormalization factors. Subsequently, a mean-field theory is employed on the renormalized Hamiltonian of the model on the honeycomb lattice under the scenario of a cooperative condensation of carriers moving in the resonating valence bond state of flavors. In particular, we find that the extended $s$-wave superconducting state is more favorable than the $d\pm id$-wave superconducting state in the doping range close to quarter filling. The pairing states of the SU(4) case reveal the property that the spin-singlet pairing and the spin-triplet pairing can coexist simultaneously. Our results might provide new insights into the twisted bilayer graphene system.

cond-mat.str-el