Vol. 74, No. 17 (2025)
2025-09-05
GENERAL
2025, 74 (17): 170302.
doi: 10.7498/aps.74.20250587
Abstract +
The spinor Bose-Einstein condensate (BEC) provides an ideal platform for observing and manipulating topological structures, which arise from the spin degrees of freedom and the superfluid nature of the gas. Artificial helicoidal spin-orbit coupling (SOC) in the spinor BEC, owing to the spatially varying gauge potential and the more flexible adjustability, provides possibly an unprecedented opportunity to search for novel quantum states. The previous studies of the BEC with helicoidal SOC mainly focus on the two-component case. However, there are few reports on the studies of helicoidal SOC in three-component BEC. Especially considering one-dimensional three-component BEC, whether the helicoidal SOC can generate previously unknown types of topological excitations and phase diagrams is still an unsolved problem. In this work, by solving quasi one-dimensional Gross-Pitaevskii equations, we study the ground state structure of one-dimensional helicoidal spin-orbit coupled three-component BEC. The numerical results show that the helicoidal SOC can induce a phase separation among the components in ferromagnetic BEC. Through numerical calculations of the system, a phase diagram is obtained as a function of the helicoidal SOC strength and gauge potential, which shows the critical conditions for phase separation and phase miscibility in ferromagnetic BEC. Meanwhile, we also study the influences of the helicoidal SOC and the gauge potential on the antiferromagnetic BEC ground state. The numerical results show that the helicoidal SOC is beneficial for the miscibility in antiferromagnetic BEC. When the helicoidal SOC strength or gauge potential increases, the ground state of antiferromagnetic BEC exhibits a stripe soliton structure. Adjusting the strength of helicoidal SOC or gauge potential can control the transitions between a plane-wave soliton and a stripe soliton. In addition, we show the changes of the particle number density maximum and the number of peaks of stripe solitons for adjusting the helicoidal SOC strength or gauge potential. Our results show that helicoidal spin-orbit coupled BEC not only provides a controlled platform for investigating the exotic topological structures, but also is crucial for the transitions between different ground states. This work paves the way for exploring the topological defect and the corresponding dynamical stability in quantum systems subjected to the helicoidal SOC in future.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
2025, 74 (17): 177101.
doi: 10.7498/aps.74.20250588
Abstract +
SPECIAL TOPIC—High-pressure modulation and in situ characterization of optoelectronic properties
2025, 74 (17): 177102.
doi: 10.7498/aps.74.20250287
Abstract +
The effects of pressure on the crystal structure, elastic properties, and electronic characteristics of Al4In2N6 are systematically studied using first-principles density functional theory. The lattice constants of Al4In2N6 decrease with the increase of pressure, exhibiting anisotropic compression with greater compressibility along the c-axis. In terms of mechanical properties, the bulk modulus increases with the increase of pressure, indicating enhanced compressive resistance. Notably, the Vickers hardness decreases with the increase of pressure, indicating that high pressure can induce plastic deformation in Al4In2N6. The calculations of elastic constants and phonon spectra confirm that Al4In2N6 retains mechanical and dynamical stability in the pressure range of 0–30 GPa. Electronic structure calculations reveal that Al4In2N6 possesses a direct band gap, and non-overlapping conduction and valence bands at the Fermi level. The conduction band has a higher carrier mobility than the valence band. The band gap increases almost linearly with pressure rising from 3.35 eV at 0 GPa to 4.24 eV at 30 GPa, demonstrating significant pressure-induced modulation of the electronic structure. Furthermore, the analysis of differential charge densities reveals that increasing pressure can strengthen the Al-N and In-N bonds in Al4In2N6 through shortened interatomic distances and stronger atomic interactions, increasing its compression resistance. In summary, this study not only deepens our understanding of the high-pressure properties of Al4In2N6 but also provides theoretical guidance for its application in UV optoelectronics. Pressure-driven modulation of its mechanical and electronic characteristics highlights its potential in efficient high-pressure optoelectronic devices and materials.
