the spin-reorientation transition from out-of-plane to in-plane in Fe/Si film is widely reported, the tuning of in-plane spin orientation is not yet well developed. Here, we report the thickness-, temperature- and Cu-...the spin-reorientation transition from out-of-plane to in-plane in Fe/Si film is widely reported, the tuning of in-plane spin orientation is not yet well developed. Here, we report the thickness-, temperature- and Cu-adsorptioninduced in-plane spin-reorientation transition processes in Fe/Si （557） film, which can be attributed to the coexistence of two competing step-induced uniaxial magnetic anisotropies, i.e., surface magnetic anisotropy with magnetization easy axis perpendicular to the step and volume magnetic anisotropy with magnetization easy axis parallel to the step. For Fe film thickness smaller than 32 monolayer （ML）, the magnitudes of two effects under various temperatures are extracted from the thickness dependence of uniaxial magnetic anisotropy. For Fe film thickness larger than 32 ML, the deviation of experimental results from fitting results is understood by the strain-relief-induced reduction of volume magnetic anisotropy. Additionally, the surface and volume magnetic anisotropies are both greatly reduced after covering Cu capping layer on Fe/Si （557） film while no significant influence of NaC1 capping layer on step-induced magnetic anisotropies is observed. The experimental results reported here provide various practical methods for manipulating in-plane spin orientation of Fe/Si films and improve the understanding of step-induced magnetic anisotropies.展开更多
Temperature dependence of magnetic switching processes with multiple jumps in Fe/MgO（001） films is investigated by magnetoresistance measurements. When the temperature decreases from 300K to 80K, the measured three-...Temperature dependence of magnetic switching processes with multiple jumps in Fe/MgO（001） films is investigated by magnetoresistance measurements. When the temperature decreases from 300K to 80K, the measured three-jump hysteresis loops turn into two-jump loops. The temperature dependence of the fourfold in-plane magnetic anisotropy constant K1, domain wall pinning energy, and an additional uniaxial magnetic anisotropy constant KUare responsible for this transformation. The strengths of K1 and domain wall pinning energy increase with decreasing temperature, but KU remains unchanged. Moreover, magnetization reversal mechanisms, with either two successive or two separate 90°domain wall propagation, are introduced to explain the multi-jump magnetic switching process in epitaxial Fe/MgO（001） films at different temperatures.展开更多
Buffer layer provides an opportunity to enhance the quality of ultrathin magnetic films. In this paper, Co films with different thickness of Co Si2 buffer layers were grown on Si（001） substrates. In order to investi...Buffer layer provides an opportunity to enhance the quality of ultrathin magnetic films. In this paper, Co films with different thickness of Co Si2 buffer layers were grown on Si（001） substrates. In order to investigate morphology, structure,and magnetic properties of films, scanning tunneling microscope（STM）, low energy electron diffraction（LEED）, high resolution transmission electron microscopy（HRTEM）, and surface magneto-optical Kerr effect（SMOKE） were used. The results show that the crystal quality and magnetic anisotropies of the Co films are strongly affected by the thickness of Co Si2 buffer layers. Few Co Si2 monolayers can prevent the interdiffusion of Si substrate and Co film and enhance the Co film quality. Furthermore, the in-plane magnetic anisotropy of Co film with optimal buffer layer shows four-fold symmetry and exhibits the two-jumps of magnetization reversal process, which is the typical phenomenon in cubic（001） films.展开更多
We present a systematic investigation of magnetic anisotropy induced by oblique deposition of Co thin films on MgO（001） substrates by molecular beam epitaxy at different deposition angles,i.e.,0？,30？,45？,60？,and...We present a systematic investigation of magnetic anisotropy induced by oblique deposition of Co thin films on MgO（001） substrates by molecular beam epitaxy at different deposition angles,i.e.,0？,30？,45？,60？,and 75？with respect to the surface normal.Low energy electron diffraction（LEED）,surface magneto–optical Kerr effect（SMOKE）,and anisotropic magnetoresistance（AMR） setups were employed to investigate the magnetic properties of cobalt films.The values of in-plane uniaxial magnetic anisotropy（UMA） constant Ku and four-fold magnetocrystalline anisotropy constant K1 were derived from magnetic torque curves on the base of AMR results.It was found that the value of Ku increases with increasing deposition angle with respect to the surface normal,while the value of K_1 remains almost constant for all the samples.Furthermore,by using MOKE results,the Ku values of the films deposited obliquely were also derived from the magnetization curves along hard axis.The results of AMR method were then compared with that of hard axis fitting method（coherent rotation） and found that both methods have almost identical values of UMA constant for each sample.展开更多
基金Project supported by the National Basic Research Program of China(Grant Nos.2015CB921403 and 2016YFA0300701)the National Natural Sciences Foundation of China(Grant Nos.51427801,11374350,11274360,and 11274361)
文摘the spin-reorientation transition from out-of-plane to in-plane in Fe/Si film is widely reported, the tuning of in-plane spin orientation is not yet well developed. Here, we report the thickness-, temperature- and Cu-adsorptioninduced in-plane spin-reorientation transition processes in Fe/Si （557） film, which can be attributed to the coexistence of two competing step-induced uniaxial magnetic anisotropies, i.e., surface magnetic anisotropy with magnetization easy axis perpendicular to the step and volume magnetic anisotropy with magnetization easy axis parallel to the step. For Fe film thickness smaller than 32 monolayer （ML）, the magnitudes of two effects under various temperatures are extracted from the thickness dependence of uniaxial magnetic anisotropy. For Fe film thickness larger than 32 ML, the deviation of experimental results from fitting results is understood by the strain-relief-induced reduction of volume magnetic anisotropy. Additionally, the surface and volume magnetic anisotropies are both greatly reduced after covering Cu capping layer on Fe/Si （557） film while no significant influence of NaC1 capping layer on step-induced magnetic anisotropies is observed. The experimental results reported here provide various practical methods for manipulating in-plane spin orientation of Fe/Si films and improve the understanding of step-induced magnetic anisotropies.
基金supported by the National Basic Research Program of China(Grant Nos.2015CB921403,2011CB921801,and 2012CB933102)the National Natural Science Foundation of China(Grant Nos.51427801,11374350,and 11274361)
文摘Temperature dependence of magnetic switching processes with multiple jumps in Fe/MgO（001） films is investigated by magnetoresistance measurements. When the temperature decreases from 300K to 80K, the measured three-jump hysteresis loops turn into two-jump loops. The temperature dependence of the fourfold in-plane magnetic anisotropy constant K1, domain wall pinning energy, and an additional uniaxial magnetic anisotropy constant KUare responsible for this transformation. The strengths of K1 and domain wall pinning energy increase with decreasing temperature, but KU remains unchanged. Moreover, magnetization reversal mechanisms, with either two successive or two separate 90°domain wall propagation, are introduced to explain the multi-jump magnetic switching process in epitaxial Fe/MgO（001） films at different temperatures.
基金Project supported by the National Basic Research Program of China(Grant Nos.2011CB921801 and 2012CB933102)the National Natural Science Foundation of China(Grant Nos.11374350,11034004,11274361,and 11274033)the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20131102130005)
文摘Buffer layer provides an opportunity to enhance the quality of ultrathin magnetic films. In this paper, Co films with different thickness of Co Si2 buffer layers were grown on Si（001） substrates. In order to investigate morphology, structure,and magnetic properties of films, scanning tunneling microscope（STM）, low energy electron diffraction（LEED）, high resolution transmission electron microscopy（HRTEM）, and surface magneto-optical Kerr effect（SMOKE） were used. The results show that the crystal quality and magnetic anisotropies of the Co films are strongly affected by the thickness of Co Si2 buffer layers. Few Co Si2 monolayers can prevent the interdiffusion of Si substrate and Co film and enhance the Co film quality. Furthermore, the in-plane magnetic anisotropy of Co film with optimal buffer layer shows four-fold symmetry and exhibits the two-jumps of magnetization reversal process, which is the typical phenomenon in cubic（001） films.
基金Project supported by the Chinese Academy of Sciences–The World Academy of Sciences(CAS–TWAS)Fellowship Programthe National Basic ResearcProgram of China(Grant Nos.2015CB921403 and 2012CB933102)the National Natural Science Foundation of China(Grant Nos.51427801,1137435and 11274361)
文摘We present a systematic investigation of magnetic anisotropy induced by oblique deposition of Co thin films on MgO（001） substrates by molecular beam epitaxy at different deposition angles,i.e.,0？,30？,45？,60？,and 75？with respect to the surface normal.Low energy electron diffraction（LEED）,surface magneto–optical Kerr effect（SMOKE）,and anisotropic magnetoresistance（AMR） setups were employed to investigate the magnetic properties of cobalt films.The values of in-plane uniaxial magnetic anisotropy（UMA） constant Ku and four-fold magnetocrystalline anisotropy constant K1 were derived from magnetic torque curves on the base of AMR results.It was found that the value of Ku increases with increasing deposition angle with respect to the surface normal,while the value of K_1 remains almost constant for all the samples.Furthermore,by using MOKE results,the Ku values of the films deposited obliquely were also derived from the magnetization curves along hard axis.The results of AMR method were then compared with that of hard axis fitting method（coherent rotation） and found that both methods have almost identical values of UMA constant for each sample.
