Magnetization reversal
A method of magnetization reversal, time stable ferrimagnetic material, a product and a domain comprising said material, a system for magnetization reversal, and information storage. Therein, a ferrimagnetic material is one in which magnetic moments of the atoms on different sublattices are opposed, as in antiferromagnetism; however, in ferrimagnetic materials, the opposing moments are unequal and a spontaneous magnetization remains.
1. A method of magnetization suitable for reversal in a multi component magnetic system in the absence of an externally applied magnetic field, the system comprising at least a first magnetic sub system and a second magnetic sub system, the first and second sub systems being coupled anti-ferromagnetically, the method comprising the steps of:
a) applying a stimulus to the magnetic system thereby reversing at least one magnetic moment of the first sub system, wherein the stimulus is an ultrafast heat pulse of less than 100 ps and is applied during a period in a first magnetization reversal time domain, and
b) relaxing and thereby reversing at least one magnetic moment of the second sub system, during a period in a second magnetization reversal time domain,
wherein the first magnetization reversal time domain is at most 100 times smaller than the second magnetization reversal time domain.
2. The method according to claim 1 , wherein the magnetic system comprises at least two non-equivalent sub systems.
3. The method according to claim 1 , wherein the stimulus is applied during a period shorter than a time of thermal equilibrium.
4. The method according to claim 3 , wherein the heat pulse is a laser pulse, wherein the wavelength of the laser pulse is from 100 nm-10000 nm.
5. The method according to claim 1 , wherein an energy density of the stimulus is from 0.05-5 mJ/cm 2 and/or wherein magnetization reversal is established in an area of the magnetic system having a cross-section of less than 250 nm.
6. The method according to claim 1 , wherein the second magnetization reversal time domain is at least 10% larger than the first magnetization reversal time domain and wherein the second magnetization reversal time domain is at most 10 times larger than the first magnetization reversal time domain, and wherein the second magnetization reversal time domain is smaller than 100 ps.
7. The method according to claim 1 , wherein the stimulus increases the temperature of an electron system having a Curie temperature to a temperature higher than the Curie temperature and/or wherein the magnetic material remains substantially at ambient temperature.