Antiferromagnetism in Ni-Based Superconductors.

Due to the lack of any magnetic order down to 1.7 K in the parent bulk compound NdNiO2 , the recently discovered 9-15 K superconductivity in the infinite-layer Nd0.8 Sr0.2 NiO2 thin films has provided an exciting playground for unearthing new superconductivity mechanisms. Herein, the successful synthesis of a series of superconducting Nd0.8 Sr0.2 NiO2 thin films ranging from 8 to 40 nm is reported. The large exchange bias effect is observed between the superconducting Nd0.8 Sr0.2 NiO2 films and a thin ferromagnetic layer, which suggests the existence of the antiferromagnetic order. Furthermore, the existence of the antiferromagnetic order is evidenced by X-ray magnetic linear dichroism measurements. These experimental results are fundamentally critical for the current field.

Giant Piezospintronic Effect in a Noncollinear Antiferromagnetic Metal.

One of the main bottleneck issues for room-temperature antiferromagnetic spintronic devices is the small signal read-out owing to the limited anisotropic magnetoresistance in antiferromagnets. However, this could be overcome by either utilizing the Berry-curvature-induced anomalous Hall resistance in noncollinear antiferromagnets or establishing tunnel-junction devices based on effective manipulation of antiferromagnetic spins. In this work, the giant piezoelectric strain modulation of the spin structure and the anomalous Hall resistance in a noncollinear antiferromagnetic metal-D019 hexagonal Mn3 Ga-is demonstrated. Furthermore, tunnel-junction devices are built with a diameter of 200 nm to amplify the maximum tunneling resistance ratio to more than 10% at room-temperature, which thus implies significant potential of noncollinear antiferromagnets for large signal-output and high-density antiferromagnetic spintronic device applications.

Anomalous Hall Effect, Robust Negative Magnetoresistance, and Memory Devices Based on a Noncollinear Antiferromagnetic Metal.

We report the successful fabrication of noncollinear antiferromagnetic D019 Mn3Ge thin films on insulating oxide substrates. The anomalous Hall effect and the large parallel negative magnetoresistance that is robust up to 53 T are observed in the thin films, which may provide evidence for the recent theoretical prediction of the existence of Weyl fermions in antiferromagnetic Mn3Ge. More importantly, we integrate the Mn3Ge thin films onto ferroelectric PMN-PT substrates and manipulate the longitudinal resistance reversibly by electric fields at room temperature, demonstrating the anisotropic magnetoresistance effect in noncollinear antiferromagnets, which thus illustrates the potential of antiferromagnetic Mn3Ge for information storage applications.

Electric-Field-Controlled Antiferromagnetic Spintronic Devices.

In recent years, the field of antiferromagnetic spintronics has been substantially advanced. Electric-field control is a promising approach for achieving ultralow power spintronic devices via suppressing Joule heating. Here, cutting-edge research, including electric-field modulation of antiferromagnetic spintronic devices using strain, ionic liquids, dielectric materials, and electrochemical ionic migration, is comprehensively reviewed. Various emergent topics such as the Néel spin-orbit torque, chiral spintronics, topological antiferromagnetic spintronics, anisotropic magnetoresistance, memory devices, 2D magnetism, and magneto-ionic modulation with respect to antiferromagnets are examined. In conclusion, the possibility of realizing high-quality room-temperature antiferromagnetic tunnel junctions, antiferromagnetic spin logic devices, and artificial antiferromagnetic neurons is highlighted. It is expected that this work provides an appropriate and forward-looking perspective that will promote the rapid development of this field.

[Application of power spectral entropy to the noninvasive detection of focal ischemic cerebral injury].

A model of SD rat focal ischemic cerebral injury is presented for use in noninvasively detecting both the extent and the location of focal ischemic cerebral injury. EEG signals of ischemic region and normal region are recorded from the moment before ischemia to 30 minutes after ischemia. Then the Power Spectral Entropy(PSE) analysis of EEG is performed. Results show that the PSE of EEG signals changes greatly as a result of focal ischemic cerebral injury. The PSE of EEG signal of ischemic region is less than that before ischemia as the ischemia lasts 15 minutes. The PSE of EEG signals of ischemic region is much less than that of normal region. These indicate that the power spectral entropy of EEG signal is a good index of focal ischemic cerebral injury and the method of power spectral entropy analysis is simple and effective.