Effect on nonlinearities in Hall measurement in liquid states

本项目是为研究液体中的霍尔效应而开发的；1)双频交流法测量时产生的假信号；2)液态时影响霍尔效应的非线性；3)交直流法及其应用。结果表明：1)通过双频交流法在样品或含放大器的测量系统中产生假信号，特别是在电极与样品溶液的界面处。假信号随外加磁场的增大而增大。信号与一号厅的许多次谐波列车相符。信号的极性符号与外加磁场的极性符号不对应。2)由于液体状态下的洛伦兹力，在外加磁场作用下出现了10^<-7>/G的电阻变化。固态或半导体样品中的值被忽略或在测量公差范围内。在金属液体，甚至电解质溶液中都会出现与磁场平方相对应的错误信号，并且在金属样品凝固后会消失。然而，它出现在铁磁性的固态，Fe， Ni和半导体薄膜，lnSb。3)即使存在非线性，我们的交直流方法也不会观察到假信号，而且该方法显示了与磁场极性相对应的符号极性，因此霍尔信号很容易与假信号区分开来。当样品电流频率超过1 kHz时，将错误信号降低到热噪声水平，在液相状态下获得具有极性符号的Ture Hall信号。在直流附近测量真实霍尔信号，外加磁场平方对应的不正确信号产生的原因及其机理，测量霍尔信号的自动评定，值得进一步研究。

The Project has been developed for the investigation of Hall effect in the liquid state ; 1) false signal generated in the measurement through Two-frequency ac method, 2) Nonlinearity affecting the Hall effect in the liquid state, 3) Ac-dc method and its application. The results are as follows,1) The false signal through the two-frequency ac method is produced in the sample or the measuring system including amplifiers, especially at the interface between a electrode and sample solution. The false signal increases with an applied magnetic field. The signal accormpanies many harmonic trains of Hall one. The polarity sign of the signal does not correspond to that of the applied magnetic field.2)The variation in resistance of 10^<-7>/G corresponding to the applied magnetic field appears due to the Lorentz force in the liquid state. The value in solid state or semiconductor sample is neglected or within measuring tolerance. An incorrect signal corresponding to the square of magnetic field appears in the liquid of metals, even electrolyte solutions, and disappears when the metal samples are solidified. However, it appears in the solid state of ferromagnetics, Fe, Ni and semiconductor film, lnSb.3)The false signals are not observed through our ac-dc method even if there existed nonlinearities, besides the method shows the sign polarity corresponding to the magnetic field polarity, therefore the Hall signal is easily distinguished from the false signal. Another incorrct signal were decreased to thermal noise level with increasing the frequency of sample current over 1 kHz, Ture Hall signals with polarity sign were obtained in the liquid states.Measring of true Hall signal nearby DC,The cause of the incorrect signal corresponding to square of applied magnetic field and its mechanism, Auto-matic evaluation on measured Hall signals, should be expected to study more.