GRAIN SIZE DEPENDENT MAGNETISM IN GRANULAR MANGANESE PEROVSKITE La0.82Sr0.18MnO3

La_0.82Sr_0.18MnO₃ have been investigated. With grain growth, both an evident decrease of magnetization and the lattice distortions have been simultaneously observed. The phenomenon suggests a structure-coupled change of magnetism in the hole-doped manganese perovskite.     

GRAIN SIZE DEPENDENT MAGNETISM IN GRANULAR MANGANESE PEROVSKITE La0.82Sr0.18MnO3

La_0.82Sr_0.18MnO₃ have been investigated. With grain growth, both an evident decrease of magnetization and the lattice distortions have been simultaneously observed. The phenomenon suggests a structure-coupled change of magnetism in the hole-doped manganese perovskite.     

SPIN-DEPENDENT INTERFACIAL TUNNELING AND MAGNETO RESISTANCE IN THE FAMILY OF GRANULAR PEROVSKITE La1-xSrxMnO*3

The magnetic transport properties in granular perovskite system La_1-xSr_xMnO^*₃ have been investigated. The spin-dependent inter facial tunneling and the corresponding giant magnetoresistance (GMR) effect have been observed in the whole temperature range below the Curie point T_c for the samp les with concentration x from 0.05 to 0.45. Theoretical analysis shows that the interfacial tunneling originates from the difference in magnetism between surfaces and cores, and the tunnel-type GMR stems from the field-induced change of interfacial magnetic order.     

用导电橡胶代替导电纸

在做模拟静电场的实验中,通常都是使用导电纸作为导电介质。但它有如下几个缺点:1.容易被探针划伤或磨损;2.更换导电纸时易起皱;3.与电极接触不太理想。针对上述缺点,可以作出如下改进:用厚度约为1mm左右的导电橡胶,按要求剪成导电纸的形状,作为导电介质。由于橡胶弹性极好,并且不易损伤,因此能很好地克服上述缺点。一般生产计算器、机厂家都有导电橡胶。如买不到或者没有合适规格的导电橡胶,也可自制,     

SPIN-DEPENDENT INTERFACIAL TUNNELING AND MAGNETO RESISTANCE IN THE FAMILY OF GRANULAR PEROVSKITE La1-xSrxMnO*3

The magnetic transport properties in granular perovskite system La_1-xSr_xMnO^*₃ have been investigated. The spin-dependent inter facial tunneling and the corresponding giant magnetoresistance (GMR) effect have been observed in the whole temperature range below the Curie point T_c for the samp les with concentration x from 0.05 to 0.45. Theoretical analysis shows that the interfacial tunneling originates from the difference in magnetism between surfaces and cores, and the tunnel-type GMR stems from the field-induced change of interfacial magnetic order.     

如何改变滑块碰撞条件

在气轨上做碰撞实验时,通常在滑块的一端弹簧上粘上适量的橡皮泥可以获得完全非弹性碰撞和弹性碰撞(如图中a),不加橡皮泥则可实现完全弹性碰撞。实际上,笔者在实验过程中发现图a所示的滑块在碰撞时不易互相粘连,尤其是在冬天,气温较低,再加上气轨上的冷风一吹,     

多功能数字电量仪的设计与应用

采用MCS-51系列单片机8031作为主芯片设计了新型多功能数字电量仪，介绍了该仪器的软、硬件设计及其在物理实验中的应用。     

Effects of quantization on detrended fluctuation analysis

Detrended fluctuation analysis(DFA) is a method foro estimating the long-range power-law correlation exponent in noisy signals.It has been used successfully in many different fields,especially in the research of physiological signals.As an inherent part of these studies,quantization of continuous signals is inevitable.In addition,coarse-graining,to transfer original signals into symbol series in symbolic dynamic analysis,can also be considered as a quantization-like operation.Therefore,it is worth considering whether the quantization of signal has any effect on the result of DFA and if so,how large the effect will be.In this paper we study how the quantized degrees for three types of noise series(anti-correlated,uncorrelated and long-range power-law correlated signals) affect the results of DFA and find that their effects are completely different.The conclusion has an essential value in choosing the resolution of data acquisition instrument and in the processing of coarse-graining of signals.