From a technological point of view one of the most important characteristics of magnetorheological fluids and ferrofluids is their fast (on the ${10}^{-3}$ s time scale) response to external magnetic fields. We report response time measurements based on the time domain magnetic susceptibility response of commercially available fluids. The dynamic susceptibility is measured over time in the presence of external magnetic field by a method using an inductive resonant circuit. The response time of the fluids is extracted as the characteristic time constant from the response to ramp excitation. We investigated the influence of the slope of the ramp excitation on the response time. The macroscopic response times were correlated with the characteristic time scales of the microscopic processes behind the susceptibility response. In case of the magnetorheological fluids the overall response time have been associated with the characteristic times of structure formation. The relatively slow response of the ferrofluid corresponded to a relaxation dominated by Brownian mechanism, which indicated the presence of multi-core clusters.

从技术角度来看，磁流变流体和铁磁流体最重要的特性之一是它们的快速（在 ${10}^{-3}$s 时间尺度）对外部磁场的响应。我们报告基于市售流体的时域磁化率响应的响应时间测量。在存在外部磁场的情况下，通过使用电感谐振电路的方法随时间测量动态磁化率。从对斜坡激励的响应中提取流体的响应时间作为特征时间常数。我们研究了斜坡激励斜率对响应时间的影响。宏观响应时间与敏感性响应背后微观过程的特征时间尺度相关。在磁流变流体的情况下，总响应时间与结构形成的特征时间相关。