Magnetic recording element
View Patent ↗A magnetic recording element is disclosed for which current density required for writing is low and structure of the element is simple. It comprises a ferromagnetic fine wire formed on a Si substrate, current electrodes that contact ends of the ferromagnetic fine wire, and voltage electrodes joined to the ferromagnetic fine wire and current electrodes to measure voltage across part of the ferromagnetic fine wire in cooperation with the current electrodes. A magnetic domain wall is induced in the ferromagnetic fine wire when the element is manufactured. A depression is formed in the surface on top of the ferromagnetic fine wire between the voltage electrodes, and between one of the current electrodes and one of the voltage electrodes. Voltage is measured between the two voltage electrodes when reading current is applied, to determine whether the magnetic domain wall is present between the two voltage electrodes, whereby recorded data can be identified.
1. A magnetic recording element, comprising:
a ferromagnetic body;
a first electrode pair joined to the ferromagnetic body; and
a second electrode pair joined (i) to a surface of the ferromagnetic body to which the first electrode pair is not joined, (ii) to part of the first electrode pair, or (iii) to both a surface of the ferromagnetic body to which the first electrode pair is not joined and to part of the first electrode pair;
wherein the second electrode pair comprises a first electrode and a second electrode in which the first electrode and the second electrode are disposed such that a potential difference arises between them when a current is passed between members of the first electrode pair,
wherein at least one of the first electrode and the second electrode is joined to the ferromagnetic body such that a gap is created between one of the first electrode pair in which a magnetic domain wall can be held, and
wherein the ferromagnetic body has at least one magnetic domain wall induced therein.
2. The magnetic recording element according to claim 1 , wherein the first electrode and the second electrode are disposed on the same surface.
3. The magnetic recording element according to claim 1 , wherein the first electrode and the second electrode are disposed on surfaces facing one another.
4. The magnetic recording element according to claim 1 , wherein the first electrode and the second electrode are disposed on surfaces adjacent to one another.
5. The magnetic recording element according to claim 1 , further comprising means for passing a current having a first current density between the first electrode pair, so as to move the magnetic domain wall through the ferromagnetic body.
6. The magnetic recording element according to claim 1 , further comprising means for passing a current having a second current density between the first electrode pair, and measuring a voltage between the second electrode pair, so as to detect the number of the magnetic domain walls present within the ferromagnetic body between positions of joints with the second electrode pair.
7. The magnetic recording element according to claim 1 , wherein the number of the magnetic domain walls present within the ferromagnetic body between positions of joints with the second electrode pair is correlated to recorded data.
8. The magnetic recording element according to claim 1 , further comprising:
means for applying a first magnetic field greater than a coercivity of the ferromagnetic body to the ferromagnetic body so as to subject the ferromagnetic body to saturation magnetization;
means for heating one of the first electrode pair joined to the ferromagnetic body so as to heat one end only of the ferromagnetic body; and
means for applying to the ferromagnetic body a second magnetic field that is anti-parallel to the first magnetic field and has a magnitude less than the coercivity and sufficient to enable only the heated portion of the ferromagnetic body to be subjected to magnetization reversal, thus subjecting only the heated portion of the ferromagnetic body to magnetization reversal so as to induce the magnetic domain wall.