Giant Zeeman splitting and zero-field splitting (ZFS) are observed in 2D nanosheets that have monolayers of atomic thickness. In this study, single-crystalline CdSe-(ethylenediamine) 0.5 and Mn 2+ -doped nanosheets are synthesized via a solvothermal process. Tunable amounts of Mn 2+ (0.5−8.0%) are introduced, resulting in lattice contraction as well as phosphorescence from five unpaired electrons. The exciton dynamics are dominated by spin-related electronic transitions ( 4 T 1 → 6 A 1 ) with long lifetimes (20.5, 132, and 295 μs). Temperature-varied EPR spectroscopy with spectral simulation reveals large ZFS (D = 3850 MHz) due to axial distortion of substituted Mn 2+ (S = 5/2). In the magnetic circular dichroism (MCD) measurements, we observed giant Zeeman splitting with large effective g values (up to 231 ± 21), which implies huge sp−d exchange interactions in 2D monolayer regimes, leading to diluted magnetic semiconductor (DMS) materials.

When thousands of new peers seek to join the peer-to-peer (P2P) system within a very short time (i.e., the so-called flash crowd event), most of the peers suffer a long startup delay as a result of peer over-competition. Accordingly, recent studies have proposed a slot-based user access control (UAC) mechanism, which periodically admits a certain number of new peers to the system, and a user batch join (UBJ) mechanism, which preconstructs the new peers into a fixed-size tree structure before peer join process. However, in the UAC mechanism, it is difficult to determine the optimal time slot length; while in the UBJ mechanism, it is difficult to determine the optimal tree size. Accordingly, the present study proposes a structured access control (SAC) mechanism, in which the new-arriving peers are preconstructed to a flexible multilayer structure to overcome the limitation of a fixed-size tree structure, and the number of peers in each layer of the structure is determined based on a consideration of the remaining upload bandwidth of the P2P system. Based on the assumption of a heterogeneous upload bandwidth capability of the peers, an analytical model is derived to describe the growth behavior of a P2P system with access control. It is shown that the simulation results for the growth rate of a P2P system based on the SAC mechanism are in good agreement with those obtained from the analytical model. In addition, the simulation results show that the SAC mechanism outperforms the UAC and UBJ mechanisms in terms of a more rapid system growth and a shorter average startup delay.