Magnetizability

Thirdly, induced properties are those that measure the response of a system to an applied field. I will concentrate on polarizabilities (for which the external field is electric) and magnetizabilities (for which the apphed field is magnetic) in a later chapter. 

The second-order terms give the magnetizability. The first term is known as the diamagnetic part and it is particularly easy to calculate since it is just the expectation value of the second moment operators. The second term is called the paramagnetic part. 

The second derivative is the magnetizability (the corresponding maeroseopic quantity is called the magnetie susceptibility /). 

The second-order term, the magnetizability, has two components. The derivative expression (10.31) is... 

The first term is referred to as the diamagnetic contribution, while the latter is the paramagnetic part of the magnetizability. Each of the two components depend on the selected gauge origin however, for exact wave functions these cancel exactly. For approximate wave functions this is not guaranteed, and as a result the total property may depend on where the origin for the vector potential (eq. (10.61)) has been chosen. 

This method was used, for example, for the solid-phase immunoassay of thyroxine (affinity chromatography). Various activation methods (CDI, periodate, and cyanogen bromide procedures) were compared with each other for coupling antibodies to magnetizable cellulose/iron oxide solid-phase particles. 211]... 

Similarly, the interaction with a magnetic field can be written in terms of a magnetic dipole, quadrupole, and other moments. However, the first derivative in the Taylor series expansion, in the presence of magnetic field, is the permanent magnetic dipole moment the second derivative is the magnetizability. For a further study on the electrical and magnetic properties, one can refer to Dykstra [9]. 

Likewise the electronic contribution to the rotational g tensor is proportional to the paramagnetic part of the magnetizability... 

Fig. 5 Components of the magnetizability tensor plotted as function of R for the B state ofH2...

Analogous quantities to die electric moments can be defined when the external perturbation takes the form of a magnetic field. In this instance die first derivative defines the permanent magnetic moment (always zero for non-degenerate electronic states), the second derivative the magnetizability or magnetic susceptibility, etc. 

Artificial Magnetic Fluids. The concept of magnetizable liquids dates hack over several decades. The first breakthrough occurred in the mid-1960s, with the production of stable colloids ol subdomain solid... 

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