Ferromagnetic Ni-Mn-Ga films were fabricated by depositing on MgO （001） substrates at temperatures from 673 K to 923 K. Microstructure, crystal structure, martensitic transformation behavior, and magnetic properties...Ferromagnetic Ni-Mn-Ga films were fabricated by depositing on MgO （001） substrates at temperatures from 673 K to 923 K. Microstructure, crystal structure, martensitic transformation behavior, and magnetic properties of the films were studied. With increasing deposition temperature, the surface morphology of the films transforms from granular to continu- ous. The martensitic transformation temperature is not dependent on deposition temperature; while transformation behavior is affected substantially by deposition temperature. X-ray analysis reveals that the film deposited at 873 K has a 7M marten- site phase, and its magnetization curve provides a typical step-increase, indicating the occurrence of magnetically induced reorientation （MIR）. In situ magnetic domain structure observation on the film deposited at 873 K reflects that the marten- sitic transformation could be divided into two periods： nucleation and growth, in the form of stripe domains. The MIR occurs at the temperature at which martensitic transformation starts, and the switching field increases with the decrease of temperature due to damped thermal activation. The magnetically induced martensitic transformation is related to the difference of magnetization between martensite and austenite. A shift of martensite temperature of dT/dH = 0.43 K/T is observed, consistent with the theoretical value, 0.41 K/T.展开更多
Ferromagnetic shape memory Ni-Mn-Ga films with 7M modulated structure were prepared on MgO （001） substrates by magnetron sputtering. Magnetization process with a typical two-hysteresis loop indicates the occurrence ...Ferromagnetic shape memory Ni-Mn-Ga films with 7M modulated structure were prepared on MgO （001） substrates by magnetron sputtering. Magnetization process with a typical two-hysteresis loop indicates the occurrence of the reversible magnetic field-induced reorientation. Magnetic domain structure and twin structure of the film were controlled by the in- terplay of the magnetic and temperature field. With cooling under an out-of-plane magnetic field, the evolution of magnetic domain structure reveals that martensitic transformation could be divided into two periods： nucleation and growth. With an in-plane magnetic field applied to a thermomagnetic-treated film, the evolution of magnetic domain structure gives evidence of a reorientation of twin variants of martensite. A microstructural model is described to define the twin structure and to produce the magnetic domain structure at the beginning of martensitic transformation; based on this model, the relationship between the twin structure and the magnetic domain structure for the treated film under an in-plane field is also described.展开更多
Ni55.5Mn21Ga23.5 and Ni54Mn22Ga23Sml films were prepared by radio frequency （RF） magnetron sputtering. The effect of Sm do- pant on the morphologic and magnetic properties of Ni55.5Mn21Ga23.5 films was investigated....Ni55.5Mn21Ga23.5 and Ni54Mn22Ga23Sml films were prepared by radio frequency （RF） magnetron sputtering. The effect of Sm do- pant on the morphologic and magnetic properties of Ni55.5Mn21Ga23.5 films was investigated. Sm doping can refine the particle size of the films from 100 to 60 nm, and further grain growth is not occurs even after annealing at 1073 K for 3.6 ks. Compared to Ni55.5Mn21Ga23.5 films, Sm-doped Ni54Mn22Ga23Sml films are easier to be magnetized and have a lower martensitic transformation temperature. In addition, the Curie temperature can also be adjusted, decreasing from 350 to 325 K after Sm doping. Martensitic transformation is not observed in the Sm-free films, which is close to the Curie temperature in the Sm-doped films, giving rise to the overlap of the structural and magnetic transi- tion temperatures.展开更多
A new thin film pulse transformer for using in ISND and model systems is fabricated by a mask sputtering process. This novel pulse transformer consists of four I-shaped CoZrRe nanometer crystal magnetic-film cores and...A new thin film pulse transformer for using in ISND and model systems is fabricated by a mask sputtering process. This novel pulse transformer consists of four I-shaped CoZrRe nanometer crystal magnetic-film cores and a Cu thin film coil, deposited on the micro-crystal glass substrate directly. The thickness of thin film core is between 1 and 3 μm, and the area is between 4mm×6 mm and 12mm×6 mm. The coils provide a relatively high induce of 0.8 μm and can be well operated in a frequency range of 0.001~20 MHz.展开更多
Three electrodeposited Fe-Ni,Fe-Co,and Fe-Ni-Co cores of thin film transformer are prepared on silicon(100) substrates,which are sputtered a 90 nm thick film of Cu acting as the seed layer.The core films consisting of...Three electrodeposited Fe-Ni,Fe-Co,and Fe-Ni-Co cores of thin film transformer are prepared on silicon(100) substrates,which are sputtered a 90 nm thick film of Cu acting as the seed layer.The core films consisting of Fe-Ni 20:80,Fe-Co 60:40 and Fe-Ni-Co 10:60:30,respectively,are deposited using direct current electrodeposition.The surface texture,electrical and magnetic properties are surveyed by scanning electron microscopy(SEM),superconducting quantum interference device(SQUID),etc.The wave transmission ability and efficiency of thin film transformer with these cores,inputting the sine wave,are compared.All the analyses indicate that FeNi alloy films display the optimal magnetic properties and excellent transformer performance.展开更多
The effects of high magnetic field armealihng on the morphology and texture of pulsed-electrodeposited Co-Ni-P films were investigated by field emission scanning electronic microscopy(FE-SEM),atomic force microscopy(A...The effects of high magnetic field armealihng on the morphology and texture of pulsed-electrodeposited Co-Ni-P films were investigated by field emission scanning electronic microscopy(FE-SEM),atomic force microscopy(AFM) and X-ray diffraction(XRD).The as-deposited film with cluster structural on a rough surface changed into non-uniform and bigger nanocrystalline during the no-field annealing due to a recrystallization process.Post-deposition annealing under a magnetic field favored to form a more homogeneous surface with smaller grain size and lower roughness.The magneto-induced a mixed phase structure including fcc-Ni,hcp-Co and fcc-CoNiP appeared in the case of the films annealed at a 9T magnetic field.The possible overlapping effects such as diffusion and recrystallization obtained by the magnetic field annealing on the morphology evolution and on the phase transformation in the films were interpreted.展开更多
基金Project supported by the National Key Project of Fundamental Research of China (Grant No.2012CB932304)the National Natural Science Foundation of China (Grant No.50831006)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Ferromagnetic Ni-Mn-Ga films were fabricated by depositing on MgO （001） substrates at temperatures from 673 K to 923 K. Microstructure, crystal structure, martensitic transformation behavior, and magnetic properties of the films were studied. With increasing deposition temperature, the surface morphology of the films transforms from granular to continu- ous. The martensitic transformation temperature is not dependent on deposition temperature; while transformation behavior is affected substantially by deposition temperature. X-ray analysis reveals that the film deposited at 873 K has a 7M marten- site phase, and its magnetization curve provides a typical step-increase, indicating the occurrence of magnetically induced reorientation （MIR）. In situ magnetic domain structure observation on the film deposited at 873 K reflects that the marten- sitic transformation could be divided into two periods： nucleation and growth, in the form of stripe domains. The MIR occurs at the temperature at which martensitic transformation starts, and the switching field increases with the decrease of temperature due to damped thermal activation. The magnetically induced martensitic transformation is related to the difference of magnetization between martensite and austenite. A shift of martensite temperature of dT/dH = 0.43 K/T is observed, consistent with the theoretical value, 0.41 K/T.
基金supported by the National Key Project of Fundamental Research of China(Grant No.2012CB932304)the National Natural Science Foundation of China(Grant No.50831006)+1 种基金the Program for New Century Excellent Talents in University(Grant No.NCET-11-0156)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Ferromagnetic shape memory Ni-Mn-Ga films with 7M modulated structure were prepared on MgO （001） substrates by magnetron sputtering. Magnetization process with a typical two-hysteresis loop indicates the occurrence of the reversible magnetic field-induced reorientation. Magnetic domain structure and twin structure of the film were controlled by the in- terplay of the magnetic and temperature field. With cooling under an out-of-plane magnetic field, the evolution of magnetic domain structure reveals that martensitic transformation could be divided into two periods： nucleation and growth. With an in-plane magnetic field applied to a thermomagnetic-treated film, the evolution of magnetic domain structure gives evidence of a reorientation of twin variants of martensite. A microstructural model is described to define the twin structure and to produce the magnetic domain structure at the beginning of martensitic transformation; based on this model, the relationship between the twin structure and the magnetic domain structure for the treated film under an in-plane field is also described.
基金supported by the National Natural Science Foundation of China (No. 61178067)the Natural Science Foundation of Shanxi Province, China (No.2010011032-1)+1 种基金the Graduate Innovation Fund of Shanxi Province, China (Grants No.20093096)the Taiyuan University Innovation and Entrepreneurship Thematic Projects (No. 100115154)
文摘Ni55.5Mn21Ga23.5 and Ni54Mn22Ga23Sml films were prepared by radio frequency （RF） magnetron sputtering. The effect of Sm do- pant on the morphologic and magnetic properties of Ni55.5Mn21Ga23.5 films was investigated. Sm doping can refine the particle size of the films from 100 to 60 nm, and further grain growth is not occurs even after annealing at 1073 K for 3.6 ks. Compared to Ni55.5Mn21Ga23.5 films, Sm-doped Ni54Mn22Ga23Sml films are easier to be magnetized and have a lower martensitic transformation temperature. In addition, the Curie temperature can also be adjusted, decreasing from 350 to 325 K after Sm doping. Martensitic transformation is not observed in the Sm-free films, which is close to the Curie temperature in the Sm-doped films, giving rise to the overlap of the structural and magnetic transi- tion temperatures.
文摘A new thin film pulse transformer for using in ISND and model systems is fabricated by a mask sputtering process. This novel pulse transformer consists of four I-shaped CoZrRe nanometer crystal magnetic-film cores and a Cu thin film coil, deposited on the micro-crystal glass substrate directly. The thickness of thin film core is between 1 and 3 μm, and the area is between 4mm×6 mm and 12mm×6 mm. The coils provide a relatively high induce of 0.8 μm and can be well operated in a frequency range of 0.001~20 MHz.
基金supported by the National Natural Science Foundation of China (Grant No. 60874101)
文摘Three electrodeposited Fe-Ni,Fe-Co,and Fe-Ni-Co cores of thin film transformer are prepared on silicon(100) substrates,which are sputtered a 90 nm thick film of Cu acting as the seed layer.The core films consisting of Fe-Ni 20:80,Fe-Co 60:40 and Fe-Ni-Co 10:60:30,respectively,are deposited using direct current electrodeposition.The surface texture,electrical and magnetic properties are surveyed by scanning electron microscopy(SEM),superconducting quantum interference device(SQUID),etc.The wave transmission ability and efficiency of thin film transformer with these cores,inputting the sine wave,are compared.All the analyses indicate that FeNi alloy films display the optimal magnetic properties and excellent transformer performance.
基金Item Sponsored by National Natural Science Foundation of China[No.51061130557,51101032]Agence Nationale de la Recherche France[No.2010-INTB-903-01]
文摘The effects of high magnetic field armealihng on the morphology and texture of pulsed-electrodeposited Co-Ni-P films were investigated by field emission scanning electronic microscopy(FE-SEM),atomic force microscopy(AFM) and X-ray diffraction(XRD).The as-deposited film with cluster structural on a rough surface changed into non-uniform and bigger nanocrystalline during the no-field annealing due to a recrystallization process.Post-deposition annealing under a magnetic field favored to form a more homogeneous surface with smaller grain size and lower roughness.The magneto-induced a mixed phase structure including fcc-Ni,hcp-Co and fcc-CoNiP appeared in the case of the films annealed at a 9T magnetic field.The possible overlapping effects such as diffusion and recrystallization obtained by the magnetic field annealing on the morphology evolution and on the phase transformation in the films were interpreted.
