Loss of Permanent Magnet Magnetization Due to Cold Temperatures Exposure
Loss of magnetization due to cold temperatures exposure is a phenomenon that occurs in various types of materials, particularly in magnetic materials. This phenomenon is commonly known as the “superparamagnetic effect” or “temperature-dependent magnetization.” It results from the thermal agitation of the atomic spins in the material, which causes the magnetic domains to fluctuate and eventually align with the external magnetic field. In this essay, we will discuss the factors that contribute to the loss of magnetization due to cold temperatures exposure, the various materials that are affected, and the implications of this phenomenon.
Factors contributing to the loss of magnetization
There are several factors that contribute to the loss of magnetization due to cold temperatures exposure. These factors include:
Thermal agitation: As the temperature of a material decreases, the thermal energy available to the atoms and molecules also decreases. This reduction in thermal energy leads to a decrease in the random motion of the atomic spins, resulting in a decrease in the magnetic domains’ ability to align with the external magnetic field.
Domain size: The size of the magnetic domains in a material plays a significant role in the loss of magnetization due to cold temperatures exposure. Smaller magnetic domains have a higher probability of aligning with the external magnetic field, while larger domains require more thermal energy to overcome the domain wall energy barriers and align with the external magnetic field.
Material properties: The specific material properties, such as the Curie temperature and the magnetic anisotropy, also play a role in determining the loss of magnetization due to cold temperatures exposure. The Curie temperature is the temperature at which a ferromagnetic material transitions to a paramagnetic material, while magnetic anisotropy refers to the preference of the material to align its magnetic domains in a specific direction.
Can a magnet be damaged by cold temperatures?
A magnet exposed to very cold temperatures can experience a loss of performance, but this happens very differently depending on the magnetic material. Ferrite magnets are easily damaged while neodymium ones have a totally different behavior.
Is it ok to expose neodymium magnets to very cold temperatures?
Actually, Neodymium magnets become slightly stronger up to -125°C. Beyond this threshold the magnetic force will steadily decrease. At -196 °C (as when immersed in liquid nitrogen), only about 85-90% of the magnetization is retained. When brought back above 125°C the adhesive force will be fully restored to original values.
Can ferrite magnets be damaged by cold temperatures?
Yes, ferrite magnets can incur a permanent loss of magnetization when exposed to temperatures below -40°C.
Magnetic products different from standard magnets are even more susceptible to low temperatures. For example, magnetic tapes and sheets can already be damaged at temperatures of -20°C. Loss of magnetization cold exposure
Implications of the loss of magnetization
The loss of magnetization due to cold temperatures exposure has several implications, including:
Reduced performance of magnetic devices: The loss of magnetization can lead to a decrease in the performance of magnetic devices, such as hard disk drives, magnetic sensors, and transformers.
Energy efficiency: In some applications, the loss of magnetization due to cold temperatures exposure can result in increased energy efficiency, as the reduced magnetization requires less energy to achieve the desired magnetic field.
Materials development: Understanding the factors that contribute to the loss of magnetization due to cold temperatures exposure can help in the development of new materials with improved magnetic properties, such as lower temperature-dependent magnetization and higher energy efficiency.
In conclusion, the loss of magnetization due to cold temperatures exposure is a phenomenon that occurs in various types of materials, with factors such as thermal agitation, domain size, and material properties contributing to the decrease in magnetization. Several materials are affected by this phenomenon, including ferromagnetic, ferrimagnetic, antiferromagnetic, and paramagnetic materials. The implications of the loss of magnetization include reduced performance in magnetic devices, increased energy efficiency, and the potential for materials development with improved magnetic properties.