Novel-morphological Fe₃O₄ nanosheets with magnetochromatic property have been prepared by a modified solvothermal method. Such nanosheets could form one-dimension photonic crystal under an external magnetic field. The Fe₃O₄ nanosheets suspension could strongly diffract visible light and display varied colors with changing the intensity of the magnetic field. The photonic response is rapid, fully reversible and widely tunable in the entire visible spectrum. Excellent magnetic properties of these Fe₃O₄ nanosheets are exhibited with a high saturation magnetization (82.1 emu/g), low remanence (13.85 emu/g) and low coercive force (75.95 Oe). The amount of the solvent diethylene glycol (DEG) plays a key role in the formation of the sheet-shaped morphology. When the ratio of the DEG reaches 100%, the growing of the crystal plane (111) of Fe₃O₄ is inhibited and the sheet-like Fe₃O₄ crystals are formed.

Topological stability is an important property for topological materials. However, the non-Hermitian effects may change this situation. Here, we investigate the robustness of edge states in the non-Hermitian Kitaev chain with an imbalanced tunneling term and a superconducting pairing term. By defining the similarity of Majorana zero modes (MZMs) and magnetic factor, the coalescing phase diagram of the MZMs and corresponding spin polarization phase diagram are provided. Because of the non-Hermitian coalescence effect and non-Hermitian suppression effect induced by the breakdown of sublattice symmetry and particle-hole symmetry, the system emerges with very interesting phenomena, such as defective MZMs, number-anomalous bulk-boundary correspondence, coalescence of many-body ground states, and the magnetic phase crossover without gap closing. Those non-Hermitian effects offer fresh insights into MZMs and topological physics.

Fe ₃ O ₄ @SiO ₂ particles were prepared on the gram-scale by selecting Na ₃ Cit as the modifier with binary solvent and were assembled into colloidal amorphous arrays with unique and attractive optical properties for EPD.

We investigate non-Hermitian spectrum and multistability of exciton-polariton condensates excited by a nonresonant pump. An increase in pumping power moves the system away from non-Hermitian spectrum degeneracy toward bifurcation through an exceptional point, which induces a transition from monostability to multistability. The spectrum can be used as a universal method for detecting this transition. In the region of multistability, the system contains one steady and two metastable states. The analyses of stability show that metastable states maintain a finite lifetime and eventually evolve into steady states, which are induced by non-Hermitian skin effects. We also discover a steady state with multipeak soliton for attractive polariton-polariton interaction, which is different from general single-peak soliton for repulsive interaction. Our results open up exciting possibilities for controlling non-Hermitian quantum multistable states, which may be useful for designing polariton-based devices exploiting optical multistability.

A facile synthetic method for magnetochromatic Fe₃O₄ nanoparticles (FNPs) with controllable size and optical properties has been fabricated by the combination of an improved solvothermal method and the usage of ultrasonic irradiation in the surface modification step. The improved solvothermal method enables the alteration of the size of nanoparticles (50nm to 180nm) in a competitively convenient way by adjusting the ratio of binary solvents, including diethylene glycol (DEG) and ethylene glycol (EG). In the surface modification step, the short-chain polyacrylic acid (PAA) is added as the surfactant with ultrasound-assisted method. In this research, due to magnetically-driven assembly FNPs forming photonic crystals, the reflection peaks show blue-shift as the magnetic field is increased from 181 to 2479G. In addition, on the basis of the calculation using Bragg’s Law, the thickness of the solvent layer is measured approximately 35nm, which accounts for the magnetochromatic properties as well as excellent dispersion.

We report a spin-orbit-coupling-induced backaction cooling in an optomechanical system, composed of a spin-orbit-coupled Bose-Einstein condensate trapped in an optical cavity with one movable end mirror, by suppressing heating effects of quantum noises. The collective density excitations of the spin-orbit-coupling-mediated hyperfine states—serving as atomic oscillators equally coupled to the cavity field—trigger strongly driven atomic backaction. We find that the backaction not only revamps low-temperature dynamics of its own but also provides an opportunity to cool the mechanical mirror to its quantum-mechanical ground state. Further, we demonstrate that the strength of spin-orbit coupling also superintends dynamic structure factor and squeezes nonlinear quantum noises, like thermomechanical and photon shot noise, which enhances optomechanical features of the hybrid cavity beyond previous investigations. Our findings are testable in a realistic setup and enhance the functionality of cavity optomechanics with spin-orbit-coupled hyperfine states in the field of quantum optics and quantum computation.