In materials mechanics, “soft” means that a material will yield readily to touch or pressure. However, when we talk about soft magnetic materials, it does not mean that the materials are soft, rather, it means that the materials’ magnetism will change readily upon exerted magnetic field.

As mentioned in the last Inside Soft Magnetic Materials I, though both of the materials are called soft magnetic materials, FeCo50 is more excellent than CR1010. How can we judge a soft magnetic material’s performance quantitatively? In fact, all the information can be obtained from the B-H curve which depicts the variation of magnetic flux density (B) with the external magnetic field strength (H).

There are several kinds of soft magnetic materials. As we have seen in Inside Soft Magnetic Materials II, there are many KPIs for judging a soft magnetic material, and soft magnets may be used for various frequencies, from quasi static to above 1 MHz. As a result, there is no one single kind who can beat all the others in every aspect and for the whole range of frequency. Optimum choice only exists for certain application conditions. Table 1 summarize the most common soft magnetic materials that can be found on the market and their KPIs.

Magnetic fields offer unique advantages in medical applications, particularly in robotics, thanks to their fundamental physical properties. Unlike optical or electrical signals, magnetic fields do not significantly decay when passing through biological tissues, enabling consistent control and imaging deep within the human body. Additionally, magnetic interactions are inherently biocompatible—non-toxic and non-ionizing—making them ideal for medical use. Their compatibility with MRI systems further underscores their safety and integration into clinical environments, paving the way for minimally invasive and precise interventions.