RESUMEN
Superconducting quantum interferometer device (SQUID) plays a key role in understanding electromagnetic properties and emergent phenomena in quantum materials. The technological appeal of SQUID is that its detection accuracy for the electromagnetic signal can precisely reach the quantum level of a single magnetic flux. However, conventional SQUID techniques normally can only be applied to a bulky sample and do not have the capability to probe the magnetic properties of micro-scale samples with small magnetic signals. Herein, it is demonstrated that, based on a specially designed superconducting nano-hole array, the contactless detection of magnetic properties and quantized vortices in micro-sized superconducting nanoflakes is realized. An anomalous hysteresis loop and a suppression of Little-Parks oscillation are observed in the detected magnetoresistance signal, which originates from the disordered distribution of the pinned vortices in Bi2 Sr2 CaCu2 O8+δ . Therefore, the density of pinning centers of the quantized vortices on such micro-sized superconducting samples can be quantitatively evaluated, which is technically inaccessible for conventional SQUID detection. The superconducting micro-magnetometer provides a new approach to exploring mesoscopic electromagnetic phenomena of quantum materials.
RESUMEN
Motor imagery-based brain-computer interfaces (MI-BCIs) have great application prospects in motor enhancement and rehabilitation. However, the capacity to control a MI-BCI varies among persons. Predicting the MI ability of a user remains challenging in BCI studies. We first calculated the relative power level (RPL), power spectral entropy (PSE) and Lempel-Ziv complexity (LZC) of the resting-state open and closed-eye EEG of different frequency bands and investigated their correlations with the upper and lower limbs MI performance (left hand, right hand, both hands and feet MI tasks) on as many as 105 subjects. Then, the most significant related features were used to construct a classifier to separate the high MI performance group from the low MI performance group. The results showed that the features of open-eye resting alpha-band EEG had the strongest significant correlations with MI performance. The PSE performed the best among all features for the screening of the MI performance, with the classification accuracy of 85.24%. These findings demonstrated that the alpha bands might offer information related to the user's MI ability, which could be used to explore more effective and general neural markers to screen subjects and design individual MI training strategies.
RESUMEN
Effective Mn2+ doping in a CsPbCl3 lattice utilizing manganese acetate and trimethylchlorosilane is achieved via a one-pot hot-injection synthesis method. This strongly contrasts to the previous case, where only the MnCl2 precursor was suitable for Mn2+ doping by considering the matching of bond dissociation energies between Mn-Cl and Pb-Cl. The Mn doping concentration and luminescence quantum yield are highly dependent on trimethylchlorosilane content. A new doping mechanism is proposed, where the incorporation of Mn2+ into CsPbCl3 is achieved via directly inserting [MnCl6]4- octahedra into the perovskite structure during the nucleation/growth processes instead of Mn-to-Pb cation exchange. Accordingly, increasing Cl- content in the reaction solution indeed promotes the doping of other divalent transition metal ions such as Ni2+, Cu2+ and Zn2+ in CsPbCl3 and improve the quantum yield of CsPbCl3 nanocrystals up to â¼20% compared to the undoped counterparts (â¼1%).
