Magnetic polaron-related optical properties in Ni(II)-doped CdS nanobelts: Implication for spin nanophotonic devices

Abstract

Emissions by magnetic polarons and spin-coupled d–d transitions in diluted magnetic semiconductors (DMSs) have become a popular research field due to their unusual optical behaviors. In this work, high-quality NiI2(II)-doped CdS nanobelts are synthesized via chemical vapor deposition (CVD), and then characterized by scanning electron microscopy (SEM), x-ray diffraction, x-ray photoelectron spectroscopy (XPS), and Raman scattering. At low temperatures, the photoluminescence (PL) spectra of the Ni-doped nanobelts demonstrate three peaks near the band edge: the free exciton (FX) peak, the exciton magnetic polaron (EMP) peak out of ferromagnetically coupled spins coupled with FXs, and a small higher-energy peak from the interaction of antiferromagnetic coupled Ni pairs and FXs, called antiferromagnetic magnetic polarons (AMPs). With a higher Ni doping concentration, in addition to the d–d transitions of single Ni ions at 620 nm and 760 nm, two other PL peaks appear at 530 nm and 685 nm, attributed to another EMP emission and the d–d transitions of the antiferromagnetic coupled Ni2+–Ni2+ pair, respectively. Furthermore, single-mode lasing at the first EMP is excited by a femtosecond laser pulse, proving a coherent bosonic lasing of the EMP condensate out of complicated states. These results show that the coupled spins play an important role in forming magnetic polaron and implementing related optical responses.

Realizing High-Efficiency Yellow Emission of Organic Antimony Halides via Rational Structural Design

“…Classically, the bandgap shrinkage due to the enhanced electron−phonon interaction at high temperature can cause the red shift of the emission band position, such as the common II−VI semiconductors of ZnSe and CdS. 36,37 However, in the recently reported 3D lead halide perovskites, the emission peak position moves to short wavelengths with increasing temperature due to the variable lattice deformation and valence band shift with temperature. 38 Hence, the absence of a shift of the peak 1 position at different temperatures should be attributed to the above two interactions being counteracted or balanced, while the blue shift of the peak 2 position at high temperatures can be assigned to the latter case dominating this phenomenon, and a similar behavior was also found in other lead-free metal halides, such as (MA) 4 Cu 2 Br 6 12 and (C 16 H 28 N) 2 SbCl 5 .…”

Photon–carrier–spin coupling in a one-dimensional Ni(II)-doped ZnTe nanostructure

“…For a polar semiconductor such as a DMS, the interaction between spin ions with carriers creates the carrier spin magnetic potential in charge-trapped states and produces the carrier-induced ferromagnetism in polar semiconductors. Therefore, FM polarization and free excitons (FXs) couple with longitudinal optical (LO) phonons to produce exciton MPs (EMPs) [3,4]. Moreover, MPs coupled with bound excitons (acceptor or donor) to form bound MPs (BMPs) and other different forms of MPs, such as antiferromagnetic polarons (AMPs), paramagnetic polarons and localized EMPs (LEMPs) exhibit different transport and optical responses, which are dependent on local doping distribution and dopant type [2,5].…”

“…The deep Ni acceptor in ZnTe and CdTe was induced by electron interaction near the VB with the configuration of 3d 8 , 4s 2 [9][10][11]. The Jahn-Teller (JT) effects of 3 T 1 (P) and 3 T 2 (F) of Ni +2 show the absorption near the IR and mid-IR range in II-VI cubic and hexagonal crystal structures. Carrier-induced FM behavior is normally observed at low temperature (LT), and has been reported for ZnTe and ZnO RT magnetism so far [2,4,12,13].…”

“…Meanwhile, the spin up of t 2g states is positioned just below the top of the VB that favors the AFM coupling between TM ions and valence electrons [14]. The Nidoped ZnTe in a glass matrix exhibits the octahedral coordinates of Ni ions, with the absorption band at 435 nm attributed to 3 A 2 ( 3 F) → 1 A 1 ( 1 G) [15,16]. An absorption peak at 460 nm is attributed to the 3 E( 3 F) → 1 A 1 ( 1 G) transition state of the Ni ion at tetrahedral sites (T d ).…”

“…An absorption peak at 460 nm is attributed to the 3 E( 3 F) → 1 A 1 ( 1 G) transition state of the Ni ion at tetrahedral sites (T d ). The Ni ion at octahedral sites in ZnO-CdS nanocomposite of 3F splits into 3 A 2g , 3 T 2g and 3 T 1g states with absorption peaks at 422 nm, 717 nm, 792 nm and 1187 nm, respectively. Moreover, the green emission at 547 nm is attributed to d-d transition of Ni ions at the octahedral site of ZnO-CdS nanocomposite [17,18].…”