Magnetic techniques SQUID magnetometer

The magnetic susceptibilities of dimer liquid crystals such as NC-Ph—Ph—O—(CH2>n—Ph—Ph—CN(n 9, 10) are measured by a SQUID magnetometer. The results obtained are interpreted within the framework of the RIS approximation, the effect arising from the conformational anisotropy of the flexible spacer being strictly taken into account. The order parameters of the mesogenic core axis thus estimated are found to be consistent with those directly observed at just below 7N) by the ZH NMR technique using mesogen-deuterated samples. 

Various adaptations that rely on force methods have been commercialised (the so-called Evans-Johnson-Matthey balance) or designed from readily available parts and described in the literature. The Evans method uses NMR and can provide variable temperature data on molecules in solution, but the technique is limited to a window where solvents stay liquid and solutes stay in solution. The one development that has been crucial to the more recent rapid development of this research field is the availability of relatively inexpensive and easy-to-use, variable temperature, variable field instrumentation, specifically the Superconducting Quantum Interference Device (SQUID) magnetometer. With a SQUID, it is possible, even for relatively inexperienced users, to determine the magnetic properties of a sample (typically 10-20 mg) as a function of temperature and applied field (down to 1.8 K and... 

Kum] Vibrating sample magnetometer, SQUID magnetometer techniques Magnetization... 

A variety of techniques has been used in the characterization of these materials. Superconducting transition temperatures and the magnetic susceptibility measurements (i.e., confirmation of the Meissner effect) are studied through the use of a SQUID magnetometer. Electric property characterization usually involves a simple measurement of the resistance of the sample. Finally, high-resolution transmission electron microscopy has also been widely employed in the characterization of these materials to aid in understanding their complex crystal structures. ... 

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