To study the influence of CoFeB/MgO interface on tunneling magnetoresistance （TMR）, different structures of magnetic tunnel junctions （MTJs） are successfully prepared by the magnetron sputtering technique and char...To study the influence of CoFeB/MgO interface on tunneling magnetoresistance （TMR）, different structures of magnetic tunnel junctions （MTJs） are successfully prepared by the magnetron sputtering technique and characterized by atomic force microscopy, a physical property measurement system, x-ray photoelectron spectroscopy, and transmission electron microscopy. The experimental results show that TMR of the CoFeB/Mg/MgO/CoFeB structure is evidently improved in comparison with the CoFeB/MgO/CoFeB structure because the inserted Mg layer prevents Fe-oxide formation at the CoFeB/MgO interface, which occurs in CoFeB/MgO/CoFeB MTJs. The inherent properties of the CoFeB/MgO/CoFeB, CoFeB/Fe-oxide/MgO/CoFeB and CoFeB/Mg/MgO/CoFeB MTJs are simulated by using the theories of density functions and non-equilibrium Green functions. The simulated results demonstrate that TMR of CoFeB/Fe-oxide/MgO/CoFeB MTJs is severely decreased and is only half the value of the CoFeB/Mg/MgO/CoFeB MTJs. Based on the experimental results and theoretical analysis, it is believed that in CoFeB/MgO/CoFeB MTJs, the interface oxidation of the CoFeB layer is the main reason to cause a remarkable reduction of TMR, and the inserted Mg layer may play an important role in protecting Fe atoms from oxidation, and then increasing TMR.展开更多
The transport property of electrons tunneling through arrays of magnetic and electric barriers is studied in silicene. In the tunneling transmission spectrum, the spin-valley-dependent filtered states can be achieved ...The transport property of electrons tunneling through arrays of magnetic and electric barriers is studied in silicene. In the tunneling transmission spectrum, the spin-valley-dependent filtered states can be achieved in an incident energy range which can be controlled by the electric gate voltage. For the parallel magnetization configuration, the transmission is asymmetric with respect to the incident angle θ, and electrons with a very large negative incident angle can always transmit in propagating modes for one of the spin-valley filtered states under a certain electromagnetic condition. But for the antiparallel configuration, the transmission is symmetric about θ and there is no such transmission channel. The difference of the transmission between the two configurations leads to a giant tunneling magnetoresistance （TMR） effect. The TMR can reach to 100% in a certain Fermi energy interval around the electrostatic potential. This energy interval can be adjusted significantly by the magnetic field and/or electric gate voltage. The results obtained may be useful for future valleytronic and spintronic applications, as well as magnetoresistance device based on silicene.展开更多
Magnetic tunnel junctions with ferroelectric barriers, often referred to as multiferroic tunnel junc- tions, have been proposed recently to display new functionalities and new device concepts. One of the notable predi...Magnetic tunnel junctions with ferroelectric barriers, often referred to as multiferroic tunnel junc- tions, have been proposed recently to display new functionalities and new device concepts. One of the notable predictions is that the combination of two charge polarizing states and the parallel and antiparallel magnetic states could make it a four resistance state device. We have recently studied the ferroelectric tunneling using a scanning probe technique and multiferroic tunnel junctions using ferromagnetic Lao.7Cao.3MnO3 and Lao.TSro.3MnO3 as the electrodes and ferroelectric （Ba, Sr）TiO3 as the barrier in trilayer planner junctions. We show that very thin （Ba, Sr）TiO3 films can sustain ferroelectricity up till room temperature. The multiferroic tunnel junctions show four resistance states as predicted and can operate at room temperatures.展开更多
Intelligent computing paradigms have become increasingly important for the efficient processing of massive amounts of data.However,using traditional electronic devices to implement these intelligent paradigms is curre...Intelligent computing paradigms have become increasingly important for the efficient processing of massive amounts of data.However,using traditional electronic devices to implement these intelligent paradigms is currently mismatched and limited by their energy,area,and speed.Spintronics,which exploits the magnetic and electrical properties of electrons,could break through these limitations and bring new possibilities to electrical devices.In particular,the tunneling magnetoresistance effect,merging quantum and spintronics,enables spintronic devices to be compatible with standard integrated circuits with a magnetic tunnel junction(MTJ)design,showing great potential for implementing hardware-based intelligent frameworks.In this review,we introduce the specific capabilities of MTJs,including nonvolatility,stochasticity,plasticity,and nonlinearity,which are highly favorable in artificial intelligence algorithms.We then present how these devices could impact the development of intelligent computing,including in-memory computing,probabilistic computing,and neuromorphic computing.Finally,we discuss their challenges and perspectives in intelligent hardware implementations.展开更多
基金Supported by the National Defense Advance Research Foundation under Grant No 9140A08XXXXXX0DZ106the Basic Research Program of Ministry of Education of China under Grant No JY10000925005+2 种基金the Scientific Research Program Funded by Shaanxi Provincial Education Department under Grant No 11JK0912the Scientific Research Foundation of Xi'an University of Science and Technology under Grant No 2010011the Doctoral Research Startup Fund of Xi'an University of Science and Technology under Grant No 2010QDJ029
文摘To study the influence of CoFeB/MgO interface on tunneling magnetoresistance （TMR）, different structures of magnetic tunnel junctions （MTJs） are successfully prepared by the magnetron sputtering technique and characterized by atomic force microscopy, a physical property measurement system, x-ray photoelectron spectroscopy, and transmission electron microscopy. The experimental results show that TMR of the CoFeB/Mg/MgO/CoFeB structure is evidently improved in comparison with the CoFeB/MgO/CoFeB structure because the inserted Mg layer prevents Fe-oxide formation at the CoFeB/MgO interface, which occurs in CoFeB/MgO/CoFeB MTJs. The inherent properties of the CoFeB/MgO/CoFeB, CoFeB/Fe-oxide/MgO/CoFeB and CoFeB/Mg/MgO/CoFeB MTJs are simulated by using the theories of density functions and non-equilibrium Green functions. The simulated results demonstrate that TMR of CoFeB/Fe-oxide/MgO/CoFeB MTJs is severely decreased and is only half the value of the CoFeB/Mg/MgO/CoFeB MTJs. Based on the experimental results and theoretical analysis, it is believed that in CoFeB/MgO/CoFeB MTJs, the interface oxidation of the CoFeB layer is the main reason to cause a remarkable reduction of TMR, and the inserted Mg layer may play an important role in protecting Fe atoms from oxidation, and then increasing TMR.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11547249,51501102,and 11647157)the Science Foundation for Excellent Youth Doctors of Three Gorges University,China(Grant No.KJ2014B076)
文摘The transport property of electrons tunneling through arrays of magnetic and electric barriers is studied in silicene. In the tunneling transmission spectrum, the spin-valley-dependent filtered states can be achieved in an incident energy range which can be controlled by the electric gate voltage. For the parallel magnetization configuration, the transmission is asymmetric with respect to the incident angle θ, and electrons with a very large negative incident angle can always transmit in propagating modes for one of the spin-valley filtered states under a certain electromagnetic condition. But for the antiparallel configuration, the transmission is symmetric about θ and there is no such transmission channel. The difference of the transmission between the two configurations leads to a giant tunneling magnetoresistance （TMR） effect. The TMR can reach to 100% in a certain Fermi energy interval around the electrostatic potential. This energy interval can be adjusted significantly by the magnetic field and/or electric gate voltage. The results obtained may be useful for future valleytronic and spintronic applications, as well as magnetoresistance device based on silicene.
文摘Magnetic tunnel junctions with ferroelectric barriers, often referred to as multiferroic tunnel junc- tions, have been proposed recently to display new functionalities and new device concepts. One of the notable predictions is that the combination of two charge polarizing states and the parallel and antiparallel magnetic states could make it a four resistance state device. We have recently studied the ferroelectric tunneling using a scanning probe technique and multiferroic tunnel junctions using ferromagnetic Lao.7Cao.3MnO3 and Lao.TSro.3MnO3 as the electrodes and ferroelectric （Ba, Sr）TiO3 as the barrier in trilayer planner junctions. We show that very thin （Ba, Sr）TiO3 films can sustain ferroelectricity up till room temperature. The multiferroic tunnel junctions show four resistance states as predicted and can operate at room temperatures.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFB4400201,and 2022YFB440020)the National Natural Science Foundation of China(Grant Nos.92164206,62271026,and 62001014)the Academic Excellence Foundation of BUAA for PhD Students。
文摘Intelligent computing paradigms have become increasingly important for the efficient processing of massive amounts of data.However,using traditional electronic devices to implement these intelligent paradigms is currently mismatched and limited by their energy,area,and speed.Spintronics,which exploits the magnetic and electrical properties of electrons,could break through these limitations and bring new possibilities to electrical devices.In particular,the tunneling magnetoresistance effect,merging quantum and spintronics,enables spintronic devices to be compatible with standard integrated circuits with a magnetic tunnel junction(MTJ)design,showing great potential for implementing hardware-based intelligent frameworks.In this review,we introduce the specific capabilities of MTJs,including nonvolatility,stochasticity,plasticity,and nonlinearity,which are highly favorable in artificial intelligence algorithms.We then present how these devices could impact the development of intelligent computing,including in-memory computing,probabilistic computing,and neuromorphic computing.Finally,we discuss their challenges and perspectives in intelligent hardware implementations.
