We report that,by linearly polarized pumping of different wavelengths,Kerr transients appear at zero magnetic field only in the case when GaMnAs samples are initialized at 3 K by first applying a 0.8 Tesla field and t...We report that,by linearly polarized pumping of different wavelengths,Kerr transients appear at zero magnetic field only in the case when GaMnAs samples are initialized at 3 K by first applying a 0.8 Tesla field and then returning to zero field.We find that,instead of magnetization precession,the near-band gap excitation induces a coherent out-of-plane turning of magnetization,which shows very long relaxation dynamics with no precession.When photon energy increases,the peak value of the Kerr transient increases,but it decays rapidly to the original slow transient seen under the near-band-gap excitation.展开更多
Tb0.3Dy0.7HoxFe1.95（x=0.00, 0.05, 0.10, 0.15, 0.20, 0.35, 0.50, 0.65） quaternary alloys were prepared by arc-melting and followed by annealing.The phases present and structure of the alloys were determined using a D...Tb0.3Dy0.7HoxFe1.95（x=0.00, 0.05, 0.10, 0.15, 0.20, 0.35, 0.50, 0.65） quaternary alloys were prepared by arc-melting and followed by annealing.The phases present and structure of the alloys were determined using a D8-Advance X-ray diffractometer.The magnetostriction of the alloys was studied by standard strain gauge technique.The dependence of Ho content on the structure, magnetostriction and density of the alloys was investigated in detail.The research results showed that Ho-doping did not change MgCu2-type cubic Laves structure in Tb0.3Dy0.7Fe1.95.When Ho content x≤0.2, rich rare earth phase presented in the alloys increased and magnetostriction of the alloys reduced evidently with increasing x, but for alloys with x〉0.2, the content of rich rare earth phase started to reduce and the magnetostriction increased quickly, especially at low magnetic field in the alloy with x=0.65 due to separation of rich rare earth phases on the surface of the alloy.展开更多
1 Introduction The R<sub>2</sub>Fe<sub>14</sub>B type compound （R=rare earths）is an important kind of magnetic materials. One of its important features is that it has very strong magneto-crys...1 Introduction The R<sub>2</sub>Fe<sub>14</sub>B type compound （R=rare earths）is an important kind of magnetic materials. One of its important features is that it has very strong magneto-crystalline anisotropy,which exhibits very complex characteristics with different rare earth elements. The calculations of the magneto-crystalline anisotropy for compounds Nd<sub>2</sub>Fe<sub>14</sub>B and Pr<sub>2</sub>Fe<sub>14</sub>B have been made by many researchers using point charge model, but their results展开更多
基金supported by the National Basic Research Program of China (Grant Nos. 2006CB932801, 2007CB924903, and 2007CB924904)the Special Research Programs of Chinese Academy of Sciences,the Knowledge Innovation Program of Chinese Academy of Sciences (Grant No. KJCX.YW.W09)the National Natural Science Foundation of China (Grant Nos. 60836002, 10674130, and 60521001)
文摘We report that,by linearly polarized pumping of different wavelengths,Kerr transients appear at zero magnetic field only in the case when GaMnAs samples are initialized at 3 K by first applying a 0.8 Tesla field and then returning to zero field.We find that,instead of magnetization precession,the near-band gap excitation induces a coherent out-of-plane turning of magnetization,which shows very long relaxation dynamics with no precession.When photon energy increases,the peak value of the Kerr transient increases,but it decays rapidly to the original slow transient seen under the near-band-gap excitation.
基金supported by the National Natural Science Foundation of China(50661002)Guangxi Provincial Natural Science Foundation of China (0575095)
文摘Tb0.3Dy0.7HoxFe1.95（x=0.00, 0.05, 0.10, 0.15, 0.20, 0.35, 0.50, 0.65） quaternary alloys were prepared by arc-melting and followed by annealing.The phases present and structure of the alloys were determined using a D8-Advance X-ray diffractometer.The magnetostriction of the alloys was studied by standard strain gauge technique.The dependence of Ho content on the structure, magnetostriction and density of the alloys was investigated in detail.The research results showed that Ho-doping did not change MgCu2-type cubic Laves structure in Tb0.3Dy0.7Fe1.95.When Ho content x≤0.2, rich rare earth phase presented in the alloys increased and magnetostriction of the alloys reduced evidently with increasing x, but for alloys with x〉0.2, the content of rich rare earth phase started to reduce and the magnetostriction increased quickly, especially at low magnetic field in the alloy with x=0.65 due to separation of rich rare earth phases on the surface of the alloy.
文摘1 Introduction The R<sub>2</sub>Fe<sub>14</sub>B type compound （R=rare earths）is an important kind of magnetic materials. One of its important features is that it has very strong magneto-crystalline anisotropy,which exhibits very complex characteristics with different rare earth elements. The calculations of the magneto-crystalline anisotropy for compounds Nd<sub>2</sub>Fe<sub>14</sub>B and Pr<sub>2</sub>Fe<sub>14</sub>B have been made by many researchers using point charge model, but their results
