The structure, magnetic and magnetotransport properties of La2/3Sr1/3MnO3(LSMO)/0.33(CuO, ZnO, Al2O3) compositeswere investigated to explore the role of second introduced phase. The microstructural analysis shows two ...The structure, magnetic and magnetotransport properties of La2/3Sr1/3MnO3(LSMO)/0.33(CuO, ZnO, Al2O3) compositeswere investigated to explore the role of second introduced phase. The microstructural analysis shows two kinds of grain boundaries:LSMO/LSMO and LSMO/second phase/LSMO. Two maximal resistivities appear in LSMO/0.33CuO and LSMO/0.33ZnOcomposites while the resistivity of LSMO/0.33Al2O3 decreases monotonically with increasing the temperature from 200 K to 400 K.Moreover, the temperature dependence of magnetoresistance(MR) of LSMO/0.33Al2O3 that decreases monotonically with increasingthe temperature is different from that of LSMO/0.33CuO and LSMO/0.33ZnO. A developed two-channel model consisting ofscattering model and tunneling model was proposed to fit the resistivity—temperature curves of these composites. The role of secondintroduced phase and the magnetotransport mechanism of these composites were elucidated.展开更多
In this work, we selected a magnetic-semiconductor as an interlayer and investigated the electronic transport properties in the ferromagnetic/ferromagnetic-semiconductor/ferromagnetic (FM/FS/FM) trilayers. The results...In this work, we selected a magnetic-semiconductor as an interlayer and investigated the electronic transport properties in the ferromagnetic/ferromagnetic-semiconductor/ferromagnetic (FM/FS/FM) trilayers. The results indicate that the large TMR comparable to that in ferromagnetic/metal oxide/ferromagnetic sandwich can be obtained in the FM/FS/FM multilayers with considering the spin filter effect in the magnetic semiconductor layer. Moreover, the transmission coefficient and TMR can be tuned through thickness, Rashba spin-orbit coupling strength and molecular field of the magnetic semiconductor. Our calculations could provide a way to design the semiconductor spintronic devices with excellent and controllable properties.展开更多
In this paper,we present a review of electron transport properties of magnetic granular films.Magnetic granular films are nanocomposite materials which consist of magnetic nanoparticles embedded in a nonmagnetic matri...In this paper,we present a review of electron transport properties of magnetic granular films.Magnetic granular films are nanocomposite materials which consist of magnetic nanoparticles embedded in a nonmagnetic matrix or assembling of magnetic nanoparticles.According to the style of the nonmagnetic matrix,microstructure and the electron transport mechanism of the films,the magnetic granular films were divided into three groups:(1) magnetic metal-metal granular films,(2) magnetic metal-insulator granular films and(3) magnetic nanocluster-assembled granular films.Moreover,we also systematically review the magnetic properties,transport properties and magnetoresistance effect of size-monodispersed Co and Fe nanocluster-assembled films.展开更多
The electronic structure, magnetic and half-metal properties of inorganic-organic hybrid compound [C4N2H12][FeoI （HP03）2 （（72 04）3] are investigated by using the full-potential linearized augmented plane wave （F...The electronic structure, magnetic and half-metal properties of inorganic-organic hybrid compound [C4N2H12][FeoI （HP03）2 （（72 04）3] are investigated by using the full-potential linearized augmented plane wave （FPLAPW） method within density-functional theory （DFT） calculations. The density of states （DOS）, the total energy of the cell and the spontaneous magnetic moment of [C4N2H12][FeII （HP03）2 （C2 04）3] are calculated. The calculation results reveal that the low-temperature phase of [C4N2H12][FeII （HP03）2（C204）3] exhibits a stable ferromagnetic （FM） ground state, and we find that this organic compound is a half-metal in FM state. In addition, we have calculated antiferromagnetically coupled interactions, revealing the existence of antiferromagnetic （AFM）, which is in agreement with the experiment. We have also found that [C4N2HI2][Fe4II （HP03）2（C204）3] is a semiconductor in the AFM state with a band gap of about 0.40 eV. Subsequently, the transport properties for potential thermoelectric applications have been studied in detail based on the Boltzmann transport theory.展开更多
In this review,we review the progress of research on ZnO-and In2O3-based diluted magnetic oxides(DMOs).Firstly,we present the preparation and characterization of DMOs.The former includes the preparation methods and co...In this review,we review the progress of research on ZnO-and In2O3-based diluted magnetic oxides(DMOs).Firstly,we present the preparation and characterization of DMOs.The former includes the preparation methods and conditions,and the latter includes the characterization techniques for measuring microstructures.Secondly,we introduce the magnetic and transport properties of DMOs,as well as the relationship between them.Thirdly,the origin and mechanism of the ferromagnetism are discussed.Fourthly,we introduce other related work,including computational work and pertinent heterogeneous structures,such as multilayers and magnetic tunnel junctions.Finally,we provide an overview and outlook for DMOs.展开更多
We investigated the electronic energy band and transport features of graphene superlattice with periodically modulated magnetic vector potential and electrostatic potential. It is found that both parallel magnetic vec...We investigated the electronic energy band and transport features of graphene superlattice with periodically modulated magnetic vector potential and electrostatic potential. It is found that both parallel magnetic vector potential and electrostatic potential can decisively shift Dirac point in a different way, which may be an efficient way to achieve electron or hole filter. We a/so find that applying modulated parallel and anti-parallel magnetic vector potential to the electrons can efficiently change electronic states between pass and stop states, which can be useful in designing electron or hole switches and lead to large magneto-resistance.展开更多
We have investigated the transport properties of the Dirac fermions through a ferromagnetic barrier junction on the surface of a strong topologicM insulator. The current-voltage characteristic curve and the tunneling ...We have investigated the transport properties of the Dirac fermions through a ferromagnetic barrier junction on the surface of a strong topologicM insulator. The current-voltage characteristic curve and the tunneling conductance are calculated theoretically. Two interesting transport features are predicted： observable negative differential conductances and linear conductances tunable from unit to nearly zero. These features can be magnetically manipulated simply by changing the spacial orientation of the magnetization. Our results may contribute to the development of high-speed switching and functional applications or electricalIy controlled magnetization switching.展开更多
Material functionalities strongly depend on the stoichiometry,crystal structure,and homogeneity.Here we demonstrate an approach of amorphous nonstoichiometric inhomogeneous oxides to realize tunable ferromagnetism and...Material functionalities strongly depend on the stoichiometry,crystal structure,and homogeneity.Here we demonstrate an approach of amorphous nonstoichiometric inhomogeneous oxides to realize tunable ferromagnetism and electrical transport at room temperature.In order to verify the origin of the ferromagnetism,we employed a series of structural,chemical,and electronic state characterizations.Combined with electron microscopy and transport measurements,synchrotron-based grazing incident wide angle X-ray scattering,soft X-ray absorption and circular dichroism clearly reveal that the roomtemperature ferromagnetism originates from the In0.23Co0.77O1-v,amorphous phase with a large tunable range of oxygen vacancies.The room-temperature ferromagnetism is tunable from a high saturation magnetization of 500 emu cm-3 to below 25 emu cm-3,with the evolving electrical resistivity from5×103μΩ cm to above 2.5×105 μΩ cm.Inhomogeneous nano-crystallization emerges with decreasing oxygen vacancies,driving the system towards non-ferromagnetism and insulating regime.Our work unfolds the novel functionalities of amorphous nonstoichiometric inhomogeneous oxides,which opens up new opportunities for developing spintronic materials with superior magnetic and transport properties.展开更多
文摘The structure, magnetic and magnetotransport properties of La2/3Sr1/3MnO3(LSMO)/0.33(CuO, ZnO, Al2O3) compositeswere investigated to explore the role of second introduced phase. The microstructural analysis shows two kinds of grain boundaries:LSMO/LSMO and LSMO/second phase/LSMO. Two maximal resistivities appear in LSMO/0.33CuO and LSMO/0.33ZnOcomposites while the resistivity of LSMO/0.33Al2O3 decreases monotonically with increasing the temperature from 200 K to 400 K.Moreover, the temperature dependence of magnetoresistance(MR) of LSMO/0.33Al2O3 that decreases monotonically with increasingthe temperature is different from that of LSMO/0.33CuO and LSMO/0.33ZnO. A developed two-channel model consisting ofscattering model and tunneling model was proposed to fit the resistivity—temperature curves of these composites. The role of secondintroduced phase and the magnetotransport mechanism of these composites were elucidated.
基金Sichuan Province Academic and Technical Leader Training Foundation (Grant No. 25727501)the Subject Construction Foundations of Southwest University for Nationalities (Grant No.2012XWD-S0805)
文摘In this work, we selected a magnetic-semiconductor as an interlayer and investigated the electronic transport properties in the ferromagnetic/ferromagnetic-semiconductor/ferromagnetic (FM/FS/FM) trilayers. The results indicate that the large TMR comparable to that in ferromagnetic/metal oxide/ferromagnetic sandwich can be obtained in the FM/FS/FM multilayers with considering the spin filter effect in the magnetic semiconductor layer. Moreover, the transmission coefficient and TMR can be tuned through thickness, Rashba spin-orbit coupling strength and molecular field of the magnetic semiconductor. Our calculations could provide a way to design the semiconductor spintronic devices with excellent and controllable properties.
基金supported by the National Basic Research Program of China (Grant No. 2012CB933103)the National Science Fund for Distinguished Young Scholars (Grant No. 50825101)the National Natural Science Foundation of China (Grant Nos. 50971108 and 51171158)
文摘In this paper,we present a review of electron transport properties of magnetic granular films.Magnetic granular films are nanocomposite materials which consist of magnetic nanoparticles embedded in a nonmagnetic matrix or assembling of magnetic nanoparticles.According to the style of the nonmagnetic matrix,microstructure and the electron transport mechanism of the films,the magnetic granular films were divided into three groups:(1) magnetic metal-metal granular films,(2) magnetic metal-insulator granular films and(3) magnetic nanocluster-assembled granular films.Moreover,we also systematically review the magnetic properties,transport properties and magnetoresistance effect of size-monodispersed Co and Fe nanocluster-assembled films.
基金Supported by the National Natural Science Foundation of China under Grant No.11104231
文摘The electronic structure, magnetic and half-metal properties of inorganic-organic hybrid compound [C4N2H12][FeoI （HP03）2 （（72 04）3] are investigated by using the full-potential linearized augmented plane wave （FPLAPW） method within density-functional theory （DFT） calculations. The density of states （DOS）, the total energy of the cell and the spontaneous magnetic moment of [C4N2H12][FeII （HP03）2 （C2 04）3] are calculated. The calculation results reveal that the low-temperature phase of [C4N2H12][FeII （HP03）2（C204）3] exhibits a stable ferromagnetic （FM） ground state, and we find that this organic compound is a half-metal in FM state. In addition, we have calculated antiferromagnetically coupled interactions, revealing the existence of antiferromagnetic （AFM）, which is in agreement with the experiment. We have also found that [C4N2HI2][Fe4II （HP03）2（C204）3] is a semiconductor in the AFM state with a band gap of about 0.40 eV. Subsequently, the transport properties for potential thermoelectric applications have been studied in detail based on the Boltzmann transport theory.
基金supported by China National Funds for Distinguished Young Scientists(Grant No.51025101)the National Natural Science Foundation of China(Grant Nos.11274214,11104173 and 61204097)+1 种基金the Research Fund for the Doctoral Program of Higher Education(Grant No. 20101404120002)the Youth Science Foundation of Shanxi Province (Grant Nos.2011021021-1,2011021021-2 and 2012021020-2)
文摘In this review,we review the progress of research on ZnO-and In2O3-based diluted magnetic oxides(DMOs).Firstly,we present the preparation and characterization of DMOs.The former includes the preparation methods and conditions,and the latter includes the characterization techniques for measuring microstructures.Secondly,we introduce the magnetic and transport properties of DMOs,as well as the relationship between them.Thirdly,the origin and mechanism of the ferromagnetism are discussed.Fourthly,we introduce other related work,including computational work and pertinent heterogeneous structures,such as multilayers and magnetic tunnel junctions.Finally,we provide an overview and outlook for DMOs.
基金Supported by the Key Program of the National Natural Science Foundation of China under Grant No. 10832005
文摘We investigated the electronic energy band and transport features of graphene superlattice with periodically modulated magnetic vector potential and electrostatic potential. It is found that both parallel magnetic vector potential and electrostatic potential can decisively shift Dirac point in a different way, which may be an efficient way to achieve electron or hole filter. We a/so find that applying modulated parallel and anti-parallel magnetic vector potential to the electrons can efficiently change electronic states between pass and stop states, which can be useful in designing electron or hole switches and lead to large magneto-resistance.
基金Supported by National Natural Science Foundation of China under Grant Nos.11174088,11175067,11274124
文摘We have investigated the transport properties of the Dirac fermions through a ferromagnetic barrier junction on the surface of a strong topologicM insulator. The current-voltage characteristic curve and the tunneling conductance are calculated theoretically. Two interesting transport features are predicted： observable negative differential conductances and linear conductances tunable from unit to nearly zero. These features can be magnetically manipulated simply by changing the spacial orientation of the magnetization. Our results may contribute to the development of high-speed switching and functional applications or electricalIy controlled magnetization switching.
基金supported by the National Natural Science Foundation of China (11434006, 11774199, and 51871112)the National Basic Research Program of China (2015CB921502)+1 种基金the 111 Project B13029supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DEAC02-76SF00515。
文摘Material functionalities strongly depend on the stoichiometry,crystal structure,and homogeneity.Here we demonstrate an approach of amorphous nonstoichiometric inhomogeneous oxides to realize tunable ferromagnetism and electrical transport at room temperature.In order to verify the origin of the ferromagnetism,we employed a series of structural,chemical,and electronic state characterizations.Combined with electron microscopy and transport measurements,synchrotron-based grazing incident wide angle X-ray scattering,soft X-ray absorption and circular dichroism clearly reveal that the roomtemperature ferromagnetism originates from the In0.23Co0.77O1-v,amorphous phase with a large tunable range of oxygen vacancies.The room-temperature ferromagnetism is tunable from a high saturation magnetization of 500 emu cm-3 to below 25 emu cm-3,with the evolving electrical resistivity from5×103μΩ cm to above 2.5×105 μΩ cm.Inhomogeneous nano-crystallization emerges with decreasing oxygen vacancies,driving the system towards non-ferromagnetism and insulating regime.Our work unfolds the novel functionalities of amorphous nonstoichiometric inhomogeneous oxides,which opens up new opportunities for developing spintronic materials with superior magnetic and transport properties.
