Investigation Of Spin Transport In Antiferromagnetic Insulators

Spintronics is an emerging discipline that takes spin as the research object and explores the generation,modulation,and detection of spin current in the solid system.Spintronic devices are regarded as a new generation of electronic devices due to the advantages of low energy consumption,non-volatility and high integration.Spin transport is a key process in the operation of spin-based devices that has been the focus of spintronic research in recent years.Spin transport in conductors depends on electron diffusion.Metal and semiconductor are widely studied as carriers of spin transport.In addition,since the insulator does not conduct electrons,the spin transport has long been ignored.However,since it has been demonstrated that spin can be transmitted through ferromagnetic insulators,it has been recognized that magnetically ordered insulators can also serve as carriers of spin transport.In this work,the spin transport in different kinds of antiferromagnetic insulators has been studied.Firstly,the spin transport phenomenon of high-frequency spin current in antiferromagnetic insulators is studied.The spin Seebeck effect was used to generate THz high-frequency spin current in yttrium iron garnet（YIG）/nickel oxide（Ni O）/platinum（Pt）trilayer film sample,and observe the spin transport phenomenon in 10-310 K.It is found that the spin Seebeck voltage signal is non-monotonic in 10-310 K,and a peak appeared near the Néel temperature of the Ni O film,which is similar to the temperature dependence of the spin pumping signal measured in the same device.The results show that thermally excited high-frequency spin current is also sensitive to the magnetic changes in antiferromagnetic materials like spin pumping.On the other hand,it is proved that the thermally excited high-frequency spin current can be used to detect the Néel temperature of the antiferromagnetic film.Next,the spin transport in the different kinds of antiferromagnetic insulators was studied by measuring resistance.With antiferromagnetic Cr₂O₃ as the research object,the Cr₂O₃/Pt bilayer film sample was designed.Based on the spin hall magnetoresistance,the antiferromagnetic phase transition will affect the spin transport in the Cr₂O₃/Pt bilayer film sample and affect the resistance of the adjacent Pt layer.Spin current is generated by spin Hall effect through the Cr₂O₃/Pt bilayer film within 100-310 K.The spin transport in Cr₂O₃ can be characterized by analyzing the change of Pt resistance with temperature.In order to verify the reliability of the experiment,the same experimental result was obtained on Cu O/Pt bilayers using the same experimental scheme.On the other hand,the Néel temperature of the antiferromagnetic film can also be detected by observing the resistance of adjacent Pt layer.