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Non-Magnetic Spin Polarized Scanning Tunneling Microscope Tip

IP.com Disclosure Number: IPCOM000104213D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Brady, MJ: AUTHOR [+3]

Abstract

Transition metals with a magnetic moment can emit spin polarized electrons due to the proximity of 3d electron levels to the conduction band. These electrons, emitted from a Scanning Tunneling Microscope (STM) tip, can be used to image the magnetic configuration of an adjacent surface. Soft magnetic materials cannot be imaged since the fringing fields from the ferromagnetic tip interact with, and modify the magnetic configuration of the surface being imaged. Inversely, hard magnetic materials affect the tip properties.

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Non-Magnetic Spin Polarized Scanning Tunneling Microscope Tip

      Transition metals with a magnetic moment can emit spin
polarized electrons due to the proximity of 3d electron levels to the
conduction band.  These electrons, emitted from a Scanning Tunneling
Microscope (STM) tip, can be used to image the magnetic configuration
of an adjacent surface.  Soft magnetic materials cannot be imaged
since the fringing fields from the ferromagnetic tip interact with,
and modify the magnetic configuration of the surface being imaged.
Inversely, hard magnetic materials affect the tip properties.

      Disclosed is a technique that utilizes conductive ferrimagnetic
materials such as amorphous Co-Gd, or Fe-Gd, having compensation
temperatures at which the magnetic moment of the transition metal and
rare earth sublattices cancel.  The individual atoms have their full
magnetic moment, but the external field is zero.  Ferrimagnets are
single domain at compensation so domain wall spin scattering is also
eliminated.  The magnetic anisotropy and subsequently emitted  spin
orientation can readily be controlled in these materials during
deposition.  Thin sputtered films of Fe-Gd have in-plane anisotropy
while evaporated films are perpendicular to the plane.  Gd-Co films
exhibt the opposite dependence, i.e., sputtered films are
perpendicular, while evaporated films are in-plane.  Room temperature
compensation results from approximately a 4:1 ratio of Co or Fe to
Gd.  Thus,...