Explanation on Exotic Magnetic Field Dependence of Staircase Pattern in Magneto-resistance of CrO2 Films

CrO2 薄膜磁阻阶梯图案与外来磁场依赖性的解释

• 批准号: 13650034
• 负责人: SUZUKI Katsuhiko
• 金额: $ 2.24万
• 依托单位: Miyagi National College of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650034/
• 关键词: CrO_2; Half Metal; Magneto-resistance; MFM; Temperature Dependence of Resistance; Staircase Pattern; Thermal Activation Tunneling; トンネリング; ハーフメタル; 走査型プローブ顕微鏡

The exotic staircase patterns have been found in the magenetoresistance of CrO_2 films in low temperature ranges. The temperature dependence of resistance decreased with decreasing temperature and had the minimum near about 120K. The natural logarithmic values of resistance were proportional to the inverse of temperature in two temperature ranges (high range : 50K-90K ; low range : 30K-50K).The value of the proportional coefficient was about 9.5K in the high temperature range and corresponds to 0.819meV. The value in the low temperature range was about 3.6-4.1K and does to 2.9-4.1meV. On the other hand, the value of step height in the staircase pattern was about 800μV in low magnetic field and corresponds to 0.8meV. The value in high magnetic field was about 360-390μV and does to 0.36-0.39meV. Therefore, the value of the proportional coefficient in high temperature range is close to one of step height in low field, and in low temperature, in high field.There are probably the discontinu … More ous states in grains during the existence of the magnetic domains because The CrO_2 has the half metallic band structure and the MFM images showed the polymagnetic domain structure in a grain. The scanning probe microscopic measurements showed that the present samples were granular films, which means that there are the discontinuous states between grains. These discontinuous states give rises to the temperature dependence in the resistance of the type of the activative energy.The activation energies in high and low temperature ranges must result from the discontinuous states in and between grains of films, respectively, by taking the magnitute of the coefficient and the mean free path of electrons into account. Although the value of coefficient in high temperature range depended on the magnetic field, one in low temperature range almost did not depend on the magnetic field, which supports the above model. Therefore, the exotic staircase patterns in the magnetoresitance are related to both the discontinuous states in the films and the half metallic properties. Less

在低温范围内CRO_2膜的MageNetResistance中发现了异国情调的楼梯图案。电阻的温度依赖性随温度降低而降低，最低约为120K。电阻的自然对数值与温度范围的温度逆成正比（高范围：50k-90k；低范围：30K-50K）。比例系数在高温范围内约为9.5k，对应于0.819mev。低温范围内的值约为3.6-4.1k，达到2.9-4.1mev。另一方面，在低磁场中，楼梯图案中的步长的值约为800μV，对应于0.8mev。高磁场中的值约为360-390μV，达到0.36-0.39mev。因此，比例系数在高温范围内的价值接近低场中的步进高度之一，在低温下，在磁性结构域的存在过程中，可能存在不连续的……在晶粒中，晶粒中更os的状态，因为CRO_2具有半金属带结构和MFM图像，并且显示了在晶粒中显示了聚合物的域形结构。扫描探针显微镜测量表明，当前的样品是颗粒膜，这意味着晶粒之间存在不连续状态。这些不连续状态在活动能量类型的阻力中产生了温度的依赖性。高温和低温范围内的激活能量必须来自膜中的不连续状态和之间的不连续状态，核心的幅度和平均温度范围内的平均温度范围内的磁力范围在较低的范围内依赖于高温范围，从而依赖于高温范围，该范围依赖于高温范围。 模型。因此，磁化率中的外来楼梯模式与膜中的不连续状态和半金属特性有关。较少的