# Spin-Related Micro-Photoluminescence in Fe\({}^{3+}\) Doped ZnSe Nanoribbons
## 1 Introduction  
Information technology has advanced quickly to quantum-based units, which are usually realized in nanosized structures and are small in size, high in speed and consume less energy. In these nanostructures, electrons with more quantum characters except charges could be exploited and modulated to present specific properties with higher efficiency. For example, spin-related carriers and excitons in magnetic semiconductors are the typical excitations with the potential to be applied in future devices and have attracted much attention.  
The ZnSe nanostructure is a type of important II-VI group semiconductor with a bandgap of about 2.7 eV at room temperature exhibiting excellent luminescence properties [1; 2; 3; 4]. Since the 1990s, the investigations on the properties of ZnSe nanostructures, including optics, magnetism and transport properties, have been done well in many groups [5; 6]. Specifically, transition metal ion doped ZnSe nano-materials, as a diluted magnetic semiconductor (DMS), have significant potential in optics andmagnetic physics [7; 8; 9], and have been received much attention. [PERSON] et al. studied the tunable dual emission based on Mn doped ZnSe nanocrystals [10]. [PERSON] et al. proposed that the interface between MnSe dopant and ZnSe host could be used for manipulating irradiative defects with a controllable manner [11]. In addition, the magnetic and luminescent properties of Fe doped ZnSe were also investigated by [PERSON] et al. [12]. The excellent emission properties of ZnSe nanostructures are potentially applicable for the lasing, lighting, and other optoelectronic devices [2; 13; 14; 15].  
The luminescence properties of transition metal doped semiconductor were influenced not only by the exciton recombination process but also spin-related interactions [16; 17]. Researchers have found that the exchange interaction between transition metal ions in diluted magnetic semiconductors can modify their band-edge emission and \(d\)-\(d\) transition emission [18; 19]. [PERSON] et al. reported that tunable emissions within the band gap is due to ferromagnetic coupling Mn(II) aggregates in Mn-doped CdS nanowires [20]. [PERSON] et al. reported Mn doped ZnSe nanocrystals demonstrating large Zeeman splitting by magnetic circular dichroism [7]. [PERSON] et al. studied the Fe\({}^{3+}\) doped ZnO crystal by means of emission, excitation, and magneto-optical spectroscopy, and showed that the \(d\)-\(d\) transition of isolated Fe\({}^{3+}\) ions on Zn\({}^{2+}\) lattice sites [21]. Traditionally, spin-related micro-photoluminescence study on DMS has significance for spin-related devices, bosonic laser and other spintronics applications, while alio-valence ions doped semiconductor compared with iso-valence ions show different optics and spin-related electrical properties.  
In Fe\({}^{3+}\) doped ZnSe nanoribbons, trivalent Fe ion substitutes for the divalent Zn ion site, which has a \(d^{5}\) configuration that is the same as the \(d\) configuration of Mn\({}^{2+}\). In the cubic crystal field, the ground state \({}^{6}\)S is labeled as \({}^{6}\)A\({}_{1}\) due to its spherically symmetric and non-degenerate characteristics, whereas the lowest excited state \({}^{4}\)G splits into four levels, labeled as \({}^{4}\)T\({}_{1}\), \({}^{4}\)T\({}_{2}\), \({}^{4}\)E and \({}^{4}\)A\({}_{1}\)[22]. Mainly, the unpaired redundant electrons in Fe\({}^{3+}\) can impact the emission and spin-related properties in Fe doped ZnSe nanostructures [23]. In this paper, we have prepared high quality Fe\({}^{3+}\) doped ZnSe nanoribbons and studied the temperature and power dependent emissions by micro-photoluminescence spectra and lifetime measurements, in which the spin-exciton interaction, spin-spin interaction and exciton-phonon coupling have been identified.