Room‐Temperature Magnetic Field Effect on Excitonic Photoluminescence in Perovskite Nanocrystals

Abstract

However, these devices can only be operated at cryogenic temperature. As temperature increases, the spin polarizations are quickly randomized by thermal fluctuation with the thermal energy (25 meV at 293 K) much larger than the Zeeman energy splitting. [6,10] Great efforts have been made to promote the room temperature (RT) spin-polarization, and few studies successfully used spin diffusion from a RT ferromagnet to semiconductor epitaxy layers-the so-called extrinsic MFE, to realize RT spin-polarization. [11][12][13] But the strict conditions such as elaborate device structure, high electric field, materials with high carrier mobility, and long spin diffusion length required limit their application. Semiconductors with RT intrinsic MFE could naturally avoid those problems and therefore are extremely desirable for advancing the spintronic applications. However, no such material has been reported to date.Lead halide perovskites (LHPs) offer opportunities to achieve RT intrinsic MFE because of the strong orbital moment carried by the heavy lead atoms, and further because of the σ-type direct orbital bonding in the [PbX 6 ] 4− octahedra lattice that may induce orbital ordering among electrons on excited states. The orbital interaction is often one or two orders of magnitude stronger than the spin interaction [14] and could contest with Magnetic-field-enhanced spin-polarized electronic/optical properties in semiconductors are crucial for fabricating various spintronic devices. However, this spin polarization is governed by weak spin exchange interactions and easily randomized by thermal fluctuations; therefore, it is only produced at cryogenic temperatures, which severely limits the applications. Herein, a room-temperature intrinsic magnetic field effect (MFE) on excitonic photoluminescence is achieved in CsPbX 3 :Mn (X = Cl, Br) perovskite nanocrystals. Through moderate Mn doping, the MFE is enhanced by exciton-Mn interactions, and through partial Br substitution, the MFE is stabilized at room temperature by exciton orbital ordering. The orbital ordering significantly enhances the g-factor difference between electrons and holes, which is evidenced by a parallel orbit-orbit interaction among excitons generated by circular polarized laser excitation. This study provides a clear avenue for engineering spintronic materials based on orbital interactions in perovskites.The ORCID identification number(s) for the author(s) of this article can be found under

All‐Inorganic Manganese‐Based CsMnCl3 Nanocrystals for X‐Ray Imaging

“…The representative high-resolution TEM (HRTEM) image and corresponding fast Fourier transform (FFT) pattern indicate these NCs are single crystalline with legible lattice distances of 0.37 and 0.42 nm, corresponding well to the (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) and (1-105) planes of the hexagonal CsMnCl 3 (Figure 1c). Three distinct diffraction rings can be identified from the selected area electron diffraction (SAED) pattern, which match with the (11)(12)(13)(14)(15)(16)(17)(18)(19)(20), (20)(21)(22)(23)(24)(25), and (22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40) planes of the hexagonal CsMnCl 3 (Figure 1d). To further confirm the phase of these NCs, powder X-ray di...…”

“…The peak positions are not monotonous shift with temperature and a spinodal appeared at around 120 K. From the literatures, such a tendency in Mn-doped NCs has been attributed to the Mn-Mn magnetic coupling. [23,36] Furthermore, the coupling of adjacent Mn 2+ ions leads further splitting of 6 A 1 into six multiples (S = 0-5) and 4 T 1 into four (S = 1-4). The narrowed the energy gap between 6 A 1 and 4 T 1 (Figure S10, Supporting Information) induces the red shifted emissions from Mn 2+ ions and accelerates the recombination rate.…”

Optically Induced Long-Lived Chirality Memory in the Color-Tunable Chiral Lead-Free Semiconductor (R)/(S)-CHEA4Bi2BrxI10–x (x = 0–10)

“…The spin polarization relaxation time of hybrid metal-halide perovskite materials is shorter than III–V systems, reaching the picosecond range at room temperature and nanosecond range at low temperatures. − To the best of our knowledge, there are no reports investigating the spin polarization dynamics of chiral lead-free perovskites. However, we believe that chiral perovskites should offer a high degree of spin polarization and long spin polarization relaxation times due to the unique combination of advantageous properties provided by chiral materials and lead-free HOIPs.…”

Spin-Polarized Photocatalytic CO2 Reduction of Mn-Doped Perovskite Nanoplates

“…The TEM morphological images in Figure b,c show that both CsPbBr 3 and Mn-CsPbBr 3 NPLs have a rectangular shape with an average size of around 45 nm. HR-TEM images corresponding to the (101) Miller plane of the 3D perovskite orthorhombic phase are shown in the inset of Figure b,c . The observed interplanar spacing for the (101) plane of CsPbBr 3 and Mn-CsPbBr 3 NPLs was 0.43 and 0.41 nm, respectively.…”