Field-induced Néel vector bi-reorientation of a ferrimagnetic insulator in the vicinity of compensation temperature

The spin Hall magnetoresistance(SMR)effect in Pt/Gd₃Fe₅O₁₂(Gd IG)bilayers was systematically investigated.The sign of SMR changes twice with increasing magnetic field in the vicinity of the magnetization compensation point(TM)of Gd IG.However,conventional SMR theory predicts the invariant SMR sign in the heterostructure composed of a heavy metal film in contact with a ferromagnetic or antiferromagnetic film.We conclude that this is because of the significant enhancement of the magnetic moment of the Gd sub-lattice and the unchanged moment of the Fe sub-lattice with a relatively large field,meaning that a small net magnetic moment is induced at TM.As a result,the Néel vector aligns with the field after the spin-flop transition,meaning that a bi-reorientation of the Néel vector is produced.Theoretical calculations based on the Néel’s theory and SMR theory also support our conclusions.Our findings indicate that the Néel-vector direction of a ferrimagnet can be tuned across a wide range by a relatively low external field around TM.     

基于交叉延迟线位敏阳极微通道板探测器的光子计数激光三维超分辨成像（特邀）

以未来天基态势感知对远距离空间目标高灵敏度探测与精细三维成像的潜在需求为出发点,开展以光子灵敏探测器为核心的光子计数激光三维成像系统及关键技术研究。提出了一种基于自主研制的交叉延迟线位敏阳极微通道板探测器的光子计数激光三维成像技术。首先介绍了该技术的基本原理,并从全链路建模与成像仿真特性分析的角度对其空间应用的潜力进行了研究;之后探讨了多域联合三维超分辨重建提升系统时空分辨能力的可行性;最后研制了基于交叉延迟线位敏阳极微通道板探测器的光子计数激光三维成像原理样机,在6.8 m距离处实现了距离分辨率优于5 mm的三维成像效果,证明了该技术方法的有效性。