Answer to Question #162973 in Physics for Ajay

Question

What are the features of magnetic hysterisis loop? Explain how the shape of the

loop determines the application of a magnetic material.

Answer 1

Hysteresis loops describe the magnetic response of a sample exposed to a magnetic field. The shape of a hysteresis loop can be diagnostic of the mineralogy of the sample . Ferrimagnetic minerals tend to produce narrow loops, whereas the presence of antiferromagnetic minerals causes hysteresis loops to be wider. Hysteresis parameters can also be used to estimate magnetic grain size. When measuring a hysteresis loop, the sample is exposed to a maximum field B_max and its magnetization (M) is measured as the field is reduced to zero, and increased again in the opposite direction all the way to the maximum B_max. The remanence measured at zero fields is equivalent to IRM. The field B_C necessary to reduce the magnetization to zero is called the coercive force, and can be used to estimate the bulk coercivity of the sample. At high fields, the curve M(B) becomes linear and the increase in M is due to the presence of para- or diamagnetic minerals. This high field slope is known as high-field paramagnetic susceptibility. The saturation magnetization, M_S, of a sample can be calculated from a hysteresis loop by extrapolating the linear high-field part of the loop back to B = 0. M_S is a function of all magnetic minerals (ferri- and antiferromagnetic) present in a sample.