High Density Magnetic Storage Using an Atomic Force Microscope With Optical Detection
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Martin, Y: AUTHOR [+2]
Disclosed is a technique for high density magnetic storage, based on an Atomic Force Microscope (AFM) equipped with a magnetic tip, which could achieve a storage density between one bit/(1000 angstrom)**2 and one bit/(100 angstrom)**2.
High Density Magnetic Storage Using an Atomic Force
a technique for high density magnetic
storage, based on an Atomic Force Microscope (AFM) equipped with a
magnetic tip, which could achieve a storage density between one
bit/(1000 angstrom)**2 and one bit/(100 angstrom)**2.
The need to
achieve high magnetic storage densities has
motivated the development of novel techniques. The techniques of
vertical recording and of magneto-optical recording utilize magnetic
films, where the magnetic field is perpendicular to the film surface,
and achieve higher storage densities than longitudinal recording.
force microscope with optical detection (1) provides
the attractive feature of allowing to position a tip within 100
angstrom of a surface, without touching this surface. Van der Waals
forces and/or electrostatic or magnetic forces are sensed and used to
control the tip to sample spacing. Feedback signals are operating at
rates of kHz, that could eventually be increased toward MHz.
technique uses a magnetized tip, a temperature-
dependent magnetic film, and some means to obtain a fast temperature
rise of the film. Iron and nickel tips have both been fabricated, and
their resultant magnetic field colinear to the tip direction has been
observed (2,3). A temperature-dependent magnetic film, such as TbFe
(used in magneto-optic recording), is a possible candidate, which we
used in our preliminary tests. However, the stringent optical
requirements met by TbFe for magneto-optical recording are not needed
here; other materials that may not have the oxidation problems of
TbFe would be preferred. Two means of obtaining a fast (and local)
temperature variation can be considered: by absorption of a focused
laser beam, or by passing a current between the tip and the
shows the recording configuration. The tip provides
the magnetic field to be "written" on the thermo-magnetic material.
The temperature of the material is raised in the region near the tip.
This lowers its coercivity to the point where the tip field switches
the material magnetizatio...