AI 中文总结
研究颗粒状Cr1-xFexO2低温磁阻滞后，重新分析相关数据。发现含Fe样品电阻变化呈现非单调滞后特征，磁场扫描减慢时减弱，对应约3秒弛豫时间，支持输运加权磁重构机制，Fe影响矫顽力、磁不均匀性及负磁阻。
AI 中文摘要
当电输运由少数自旋相关的晶间隧穿路径主导时，压实的CrO2粉末的低温磁阻回线变得强烈非单调。我们重新分析了先前报道的未掺杂CrO2和含Fe的Cr1-xFexO2的数据，重点关注传统低场滞后之外的额外分支交叉。在含Fe的样品中，电阻先降低，经过最小值，在扩展的场区间上升，然后在更高场再次降低。当磁场扫描减慢时，这种非单调滞后特征会大大减弱。对三个最快扫描的数字化显示，电阻开始恢复的场随扫描速率近似线性移动，对应于约3秒的有效磁输运弛豫时间。这个尺度归因于主导电流的晶间接触处局部矩和畴构型的缓慢演化。观察结果与传统的负隧穿磁阻叠加在与瞬态局部磁无序相关的较慢电阻增加贡献上一致。Fe增加矫顽力和界面磁不均匀性，同时降低整体负磁阻。结果支持了异常滞后形状的输运加权磁重构机制。
英文摘要
Low-temperature magnetoresistance loops of compacted CrO2 powders become strongly nonmonotonic when electrical transport is dominated by a small number of spin-dependent intergranular tunnelling paths. We reanalyse previously reported data for undoped CrO2 and Fe-containing Cr1-xFexO2, focusing on additional branch crossings beyond the conventional low-field hysteresis. In the Fe-containing specimen, the resistance decreases, passes through a minimum, rises over an extended field interval, and then decreases again at higher field. This nonmonotonic hysteretic feature is strongly reduced when the magnetic-field sweep is slowed. Digitization of the three fastest sweeps shows that the field at which the resistance starts to recover shifts approximately linearly with sweep rate, corresponding to an effective magnetotransport relaxation time of about 3 s. This scale is attributed not to microscopic spin flips but to the slow evolution of local moment and domain configurations at the intergranular contacts dominating the current. The observations are consistent with conventional negative tunnelling magnetoresistance superimposed on a slower resistance-increasing contribution associated with transient local magnetic disorder. Fe increases coercivity and interfacial magnetic heterogeneity while reducing the overall negative magnetoresistance. The results support a transport-weighted magnetic-reconfiguration mechanism for the unusual hysteresis shape.
Comments12 pages, 5 figures
