Sustainable Magnet Temperature
Neodymium magnets are not damaged by immersion in liquid nitrogen at a temperature of -196°C (77K). These magnets can be used without hesitation for superconductor experiments.
Ferrite Magnets lose part of their magnetisation permanently at a temperature below -40°C.
Magnetic Strips and Magnetic Sheets lose part of their magnetisation permanently at temperatures below -20°C. Temperatures under -20°C and above 80°C damages the structurual integrity of magnetic tapes and sheets. It causes the products to permanently lose part of their adhesive force. Therefore, do not use these in places with extremely high or low temperatures.
Therefore, Ferrite Magents, Magnetic Strips, and Magnetic Sheets should not be vigorously cooled.
Neodymium magnets of the type N lose part of their magnetisation permanently at a temperatures at and above 80 °C, strips and sheets at 80 °C, and ferrite magnets at 250°C.
If you heat a magnet above its "Maximum Working Temperature", it loses part of its magnetisation, and at the "Curie Temperature", there is no remanence of magnetisim left.