YCo_(5) alloy is processed by surfactant-assisted high-energy ball milling. Oleic acid is used as the surfactant and is 20% of the starting powder.The resultant particles are flakes of several microns in length and wi...YCo_(5) alloy is processed by surfactant-assisted high-energy ball milling. Oleic acid is used as the surfactant and is 20% of the starting powder.The resultant particles are flakes of several microns in length and width,and 20-200nm in thickness. The flakes have significant crystallographic anisotropy and the c-axis (also easy magnetization axes) is perpendicular to the flake's surface. Maximum coercivity of 192kA/m is obtained in the sample milled for 100 min.Excess milling results in the appearance of Fe and deteriorates the permanent magnetic properties seriously.展开更多
CrO_(2)-TiO_(2) composites are synthesized by using a high temperature and high pressure method using CrO_(3) and H_(2)TiO_(3) as precursors.The composites consist of large rod-like CrO_(2) crystals separated by small...CrO_(2)-TiO_(2) composites are synthesized by using a high temperature and high pressure method using CrO_(3) and H_(2)TiO_(3) as precursors.The composites consist of large rod-like CrO_(2) crystals separated by small TiO_(2) grains.The CrO_(2) in the composites is very pure and its saturation magnetization is very close to the theoretical value(i.e.,2μ_(B) per formula unit).The composites exhibit a large negative magnetoresistance(MR)at 5 K.The MR in CrO_(2)-TiO_(2) composites is mainly attributed to spin-polarized tunneling between CrO_(2) crystals.The conductivity of the composites is best described by a fluctuation-induced tunneling model below 230 K.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 11174104the National Fund for Fostering Talents of Basic Science under Grant No J1103202.
文摘YCo_(5) alloy is processed by surfactant-assisted high-energy ball milling. Oleic acid is used as the surfactant and is 20% of the starting powder.The resultant particles are flakes of several microns in length and width,and 20-200nm in thickness. The flakes have significant crystallographic anisotropy and the c-axis (also easy magnetization axes) is perpendicular to the flake's surface. Maximum coercivity of 192kA/m is obtained in the sample milled for 100 min.Excess milling results in the appearance of Fe and deteriorates the permanent magnetic properties seriously.
基金Supported by the National Natural Science Foundation of China under Grant No 50972048the Program for New Century Excellent Talents in University.
文摘CrO_(2)-TiO_(2) composites are synthesized by using a high temperature and high pressure method using CrO_(3) and H_(2)TiO_(3) as precursors.The composites consist of large rod-like CrO_(2) crystals separated by small TiO_(2) grains.The CrO_(2) in the composites is very pure and its saturation magnetization is very close to the theoretical value(i.e.,2μ_(B) per formula unit).The composites exhibit a large negative magnetoresistance(MR)at 5 K.The MR in CrO_(2)-TiO_(2) composites is mainly attributed to spin-polarized tunneling between CrO_(2) crystals.The conductivity of the composites is best described by a fluctuation-induced tunneling model below 230 K.
