[L1] 1 Ferromagnetic Materials [L2] 1) Definition [L4] - Materials that exhibit ferromagnetism. [L4] - Ferromagnetism: A phenomenon where all spins align spontaneously in a specific direction due to interactions between spins within the magnetic material. [L4] - Materials where atomic magnetic moments are strong because spin motions are aligned in one direction. [L2] 2) Target Materials [L4] - Transition metals: Fe (Iron), Co (Cobalt), Ni (Nickel) [L4] - Metal compounds containing rare earth atoms: Nd (Neodymium), Sm (Samarium), etc. [L2] 3) Features [L4] - At high temperatures, thermal energy causes spin fluctuations, destroying the spin alignment of ferromagnetic materials. [L4] - All ferromagnetic materials exhibit paramagnetism where the total magnetic moment becomes zero above a certain temperature. [L5] * This phase transition temperature is called the Curie temperature. [L1] 2 Paramagnetic Materials [L2] 1) Definition [L4] - Materials that are weakly magnetized in the direction of the magnetic field when placed in it, and lose magnetization when the field is removed. [L4] - Materials where atoms exhibit a magnetic moment in a certain direction because the magnetic moments caused by electron orbital motion and spin do not cancel each other out perfectly. [L2] 2) Target Materials [L4] - Metals: Al (Aluminum), Sn (Tin), Pt (Platinum), Ir (Iridium) [L4] - Non-metals: Air, Oxygen [L2] 3) Features [L4] - Ferromagnetic and paramagnetic materials have very similar magnetic field formation states; the difference lies in the degree of alignment. [L5] * In terms of magnetic susceptibility: If susceptibility is very large (50~5,000), it is Ferromagnetic. [L5] * If susceptibility is very small (0.00001), it is Paramagnetic. [L1] 3 Diamagnetic Materials [L2] 1) Definition [L4] - Weak repulsive force of a material against a magnetic field. [L5] * Diamagnetism is only confirmed when an external magnetic field is applied. [L4] - Materials where atoms do not exhibit a magnetic moment on average because magnetic moments caused by electron orbital motion and spin motion cancel each other out perfectly. [L2] 2) Target Materials [L4] - Metals: Bismuth, Copper, Gold, Silver [L4] - Non-metals: Water, Mercury, Ethanol [L2] 3) Features [L4] - All materials possess diamagnetic properties, but diamagnetism is not revealed if ferromagnetic/paramagnetic properties are greater or cancel it out. [L4] - Diamagnetic effects appear only in specific materials; diamagnetic materials form a magnetic field opposite to the external magnetic field. [L4] - Diamagnetic materials have a very small negative magnetic susceptibility (around -0.0001). [L1] 4 Nonmagnetic Materials [L4] - Nonmagnetic materials do not react to external magnetic fields and have no magnetic spin interaction with magnetic fields. [L4] - Most materials (non-metals, some metals) fall into the category of nonmagnetic materials.