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Structure of a Magnetic Tip for Scanning Probe Microscope Recording

IP.com Disclosure Number: IPCOM000114421D
Original Publication Date: 1994-Dec-01
Included in the Prior Art Database: 2005-Mar-28
Document File: 2 page(s) / 71K

Publishing Venue

IBM

Related People

Takayama, S: AUTHOR [+3]

Abstract

In recent years, various techniques have been proposed for recording bit patterns using Scanning Probe Microscopes (SPM) as described in (1). Magnetic recording by SPM is more advantageous than surface modification from the viewpoint of overwriting and erasing the written information. It is also preferable to electric charge trapping because the data can be retained for practically long time. However, the areal density of magnetic recording by SPM is limited to several Gb/in2 due to difficulty in focussing the magnetic field from the sharp magnetic tip. The size of the written magnetic dots produced by the SPM techniques are in the range of 300 to 600nm (2, 3, 4). A new technique is required to overcome this limitation.

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Structure of a Magnetic Tip for Scanning Probe Microscope Recording

      In recent years, various techniques have been proposed for
recording bit patterns using Scanning Probe Microscopes (SPM) as
described in (1).  Magnetic recording by SPM is more advantageous
than surface modification from the viewpoint of overwriting and
erasing the written information.  It is also preferable to electric
charge trapping because the data can be retained for practically long
time.  However, the areal density of magnetic recording by SPM is
limited to several Gb/in2 due to difficulty in focussing the magnetic
field from the sharp magnetic tip.  The size of the written magnetic
dots produced by the SPM techniques are in the range of 300 to  600nm
(2, 3, 4).  A new technique is required to overcome this limitation.

      The objective of this invention is to focus the magnetic field
at the tip extremity by applying a complete diamagnetic property
(x=-1) of superconductive material to the magnetic tip.  When
magnetic field is applied to the superconductor, an induced current
flows at the surface of the superconductor to prevent the magnetic
field from invading deeply into the surface.  The penetration depth
of the field is normally several 100 Angstroms.  Thus magnetic field
is suppressed if the thickness of the superconductor film is more
than several 1,000 Angstroms.

      The structure of the proposed magnetic tip is shown in the
Figure.  The tip (1) is made of magnetic material with high magnetic
permeability coated with thin film of superconductive material (2) of
thickness 1,000 to 3,000 Angstroms with a hole of several 10
nanometers
in size at the tip end.  The tip magnetization is switched by the
current through the coil (3).  The magnetic tip coated with a
diamagnetic material for force microscopy can also be excited by the
auxili...