Magnetic field observation with tunneling microscopy

Claim 1

An apparatus for observing a magnetic field alternating at a predetermined frequency near a surface of a sample that is conductive in at least said surface, the sample being connected to an alternating-magnetic-field drive circuit adapted to drive the alternating magnetic field of the sample at the predetermined frequency, comprising: (a) a cantilever; (b) a tip supported by said cantilever, at least the end of said tip having a magnetic moment; (c) means for applying a voltage between said tip and said sample surface; (d) means for maintaining a distance between said tip and said sample surface such as to permit a tunneling current to flow; and (e) means electrically coupled to said tip for extracting a component of said predetermined frequency of tunneling current caused by the interaction between said magnetic field and said magnetic moment.

Claim 2

An apparatus for observing a magnetic field alternating at a predetermined frequency near a surface of a sample that is conductive in at least said surface, the sample being connected to an alternating-magnetic-field drive circuit adapted to drive the alternating magnetic field of the sample at the predetermined frequency, comprising: (a) a cantilever; (b) a tip supported by said cantilever, at least the end of said tip having a magnetic moment; (c) means for applying a voltage between said tip and said sample surface; (d) means for maintaining a distance between said tip and said sample surface such as to permit a tunneling current to flow; and (e) means electrically coupled to said tip for extracting a component of said predetermined frequency of tunneling current caused by the interaction between said magnetic field and said magnetic moment.

Claim 5

An apparatus for simultaneously observing both the topography of a surface of a sample, which is conductive in at least said surface, and a magnetic field alternating at a predetermined frequency near the sample surface, comprising: (a) a cantilever; (b) a tip supported by said cantilever, at least the end of said tip having a magnetic moment; (c) means for applying a voltage between said tip and said sample surface; (d) alternating-magnetic-field drive means for driving the alternating magnetic field of the sample at the predetermined frequency; (e) x-direction driving means, y-direction driving means and z-direction driving means responsive to respective input signals for moving said tip in the x, y and z directions, where the x and y directions are defined to be substantially parallel to said sample surface, and the z direction is defined to be substantially perpendicular to said sample surface; (f) x-direction control means, y-direction control means, and z-direction control means for applying respective signals to said x-direction driving means, said y-direction driving means, and said z-direction driving means to scan said tip in the x and y directions while maintaining such a distance in the z direction between said tip and said sample surface as to permit a tunneling current to flow; (g) means electrically coupled to said tip and to said alternating-magnetic-field drive means for extracting a component of said predetermined frequency of a tunneling current caused by an interaction between said magnetic field and said magnetic moment; (h) a low-pass filter electrically connected to said tip; and (i) means for determining the output of said z-direction control means so as to keep the output of said low-pass filter essentially constant.

Claim 6

An apparatus for simultaneously observing both the topography of a surface of a sample, which is conductive in at least said surface, and a magnetic field alternating at a predetermined frequency near the sample surface, comprising: (a) a cantilever; (b) a tip supported by said cantilever, at least the end of said tip having a magnetic moment; (c) means for applying a voltage between said tip and said sample surface; (d) alternating-magnetic-field drive means for driving the alternating magnetic field of the sample at the predetermined frequency; (e) x-direction driving means, y-direction driving means and z-direction driving means responsive to respective input signals for moving said tip in the x, y and z directions, where the x and y directions are defined to be substantially parallel to said sample surface, and the z direction is defined to be substantially perpendicular to said sample surface; (f) x-direction control means, y-direction control means, and z-direction control means for applying respective signals to said x-direction driving means, said y-direction driving means, and said z-direction driving means to scan said tip in the x and y directions while maintaining such a distance in the z direction between said tip and said sample surface as to permit a tunneling current to flow; (g) means electrically coupled to said tip and to said alternating-magnetic-field drive means for extracting a component of said predetermined frequency of a tunneling current caused by an interaction between said magnetic field and said magnetic moment; (h) a low-pass filter electrically connected to said tip; and (i) means for determining the output of said z-direction control means so as to keep the output of said low-pass filter essentially constant.

Claim 10

An apparatus for observing a magnetic field near a surface of a sample that is conductive in at least said surface, comprising: (a) a cantilever; (b) a tip supported by said cantilever, at least the surface of the end of said tip consisting of a magnetic material; (c) means for switching the direction of the magnetic moment of said tip at a predetermined frequency; (d) means for applying a voltage between said tip and said sample surface; (e) means for maintaining a distance between said tip and said sample surface such as to permit a tunneling current to flow; and (f) means electrically coupled to said tip for extracting a component of said predetermined frequency caused by the interaction between said magnetic field and said magnetic moment.

Claim 11

An apparatus for observing a magnetic field near a surface of a sample that is conductive in at least said surface, comprising: (a) a cantilever; (b) a tip supported by said cantilever, at least the surface of the end of said tip consisting of a magnetic material; (c) means for switching the direction of the magnetic moment of said tip at a predetermined frequency; (d) means for applying a voltage between said tip and said sample surface; (e) means for maintaining a distance between said tip and said sample surface such as to permit a tunneling current to flow; and (f) means electrically coupled to said tip for extracting a component of said predetermined frequency caused by the interaction between said magnetic field and said magnetic moment.

Claim 14

An apparatus for simultaneously observing both the topography of a sample, which is conductive in at least said surface, and the magnetic field near the sample surface, comprising: (a) a cantilever; (b) a tip supported by said cantilever, at least the surface of the end of said tip consisting of a magnetic material; (c) means for switching the direction of the magnetic moment of said tip at a predetermined frequency; (d) means for applying a voltage between said tip and said sample surface; (e) x-direction driving means, y-direction driving means, and z-direction driving means responsive to respective input signals for moving said tip in the x, y and z directions, where the x and y directions are defined to be substantially parallel to said sample surface, and the z is defined to be substantially perpendicular to said sample surface; (f) x-direction control means, y-direction control means, and z-direction control means for applying respective signals to said x-direction driving means, said y-direction driving means, and said z-direction driving means to scan said tip in the x and y directions while maintaining a distance in the z direction between said tip and said sample surface such as to permit a tunneling current to flow; (g) means electrically coupled to said tip for extracting a component of said predetermined frequency of a tunneling current caused by the interaction between said magnetic field and said magnetic moment; (h) a low-pass filter electrically coupled to said tip; and (i) means for determining the output of said z-direction control means so as to keep the output of said low-pass filter essentially constant.

Claim 15

An apparatus for simultaneously observing both the topography of a sample, which is conductive in at least said surface, and the magnetic field near the sample surface, comprising: (a) a cantilever; (b) a tip supported by said cantilever, at least the surface of the end of said tip consisting of a magnetic material; (c) means for switching the direction of the magnetic moment of said tip at a predetermined frequency; (d) means for applying a voltage between said tip and said sample surface; (e) x-direction driving means, y-direction driving means, and z-direction driving means responsive to respective input signals for moving said tip in the x, y and z directions, where the x and y directions are defined to be substantially parallel to said sample surface, and the z is defined to be substantially perpendicular to said sample surface; (f) x-direction control means, y-direction control means, and z-direction control means for applying respective signals to said x-direction driving means, said y-direction driving means, and said z-direction driving means to scan said tip in the x and y directions while maintaining a distance in the z direction between said tip and said sample surface such as to permit a tunneling current to flow; (g) means electrically coupled to said tip for extracting a component of said predetermined frequency of a tunneling current caused by the interaction between said magnetic field and said magnetic moment; (h) a low-pass filter electrically coupled to said tip; and (i) means for determining the output of said z-direction control means so as to keep the output of said low-pass filter essentially constant.

Claim 19

A method for observing a magnetic field alternating at a predetermined frequency near a surface of a sample that is conductive in at least said surface, using a scanning tunneling microscope that includes a cantilever and a tip supported by said cantilever, the end at least of said tip having a magnetic moment, comprising the steps of: (a) producing a magnetic field alternating at said predetermined frequency to vibrate said tip by creating an interaction between said magnetic moment and said magnetic field while maintaining a distance between said tip and said sample surface such as to permit a tunneling current to flow; and (b) extracting a component of said predetermined frequency of said tunneling current, the component representing a measure of the magnetic field.

Claim 20

A method for observing a magnetic field alternating at a predetermined frequency near a surface of a sample that is conductive in at least said surface, using a scanning tunneling microscope that includes a cantilever and a tip supported by said cantilever, the end at least of said tip having a magnetic moment, comprising the steps of: (a) producing a magnetic field alternating at said predetermined frequency to vibrate said tip by creating an interaction between said magnetic moment and said magnetic field while maintaining a distance between said tip and said sample surface such as to permit a tunneling current to flow; and (b) extracting a component of said predetermined frequency of said tunneling current, the component representing a measure of the magnetic field.

Claim 23

The method for simultaneously observing both the topography of a surface of a sample, which is conductive in at least said surface, and a magnetic field alternating at a predetermined frequency near the sample surface by using a scanning tunneling microscope that includes a cantilever; a tip supported by said cantilever, the end at least of said tip having a magnetic moment; x-direction driving means, y-direction driving means, and z-direction driving means responsive to respective input signals for moving said tip in the x, y, and z directions, where the x and y directions are defined to be substantially parallel to said sample and the z direction is defined to be substantially perpendicular to said sample surface; x-direction control means, y-direction control means, and z-direction control means for applying respective signals to said x-direction driving means, said y-direction driving means, and said z-direction driving means, comprising the steps of: (a) producing a magnetic field alternating at said predetermined frequency to vibrate said tip by creating an interaction between said magnetic moment and said magnetic field, while scanning said tip along said sample surface and maintaining a distance between said tip and said sample surface such as to permit a tunneling current to flow to produce an alternating-magnetic-field-modulated scanned-surface-topography tunneling-current signal; (b) extracting from said alternating-magnetic-field-modulated scanned-surface-topography tunneling-current signal an alternating-magnetic-field-modulation component of said predetermined frequency; (c) eliminating from said alternating-magnetic-field-modulated scanned-surface-topography tunneling-current signal high-frequency components including said predetermined frequency to form a scanned-surface-topography tunneling-current signal component; and (d) determining the output of said z-direction control means so as to keep the scanned-surface-topography tunneling-current signal component essentially constant after removal of high-frequency components.

Claim 24

The method for simultaneously observing both the topography of a surface of a sample, which is conductive in at least said surface, and a magnetic field alternating at a predetermined frequency near the sample surface by using a scanning tunneling microscope that includes a cantilever; a tip supported by said cantilever, the end at least of said tip having a magnetic moment; x-direction driving means, y-direction driving means, and z-direction driving means responsive to respective input signals for moving said tip in the x, y, and z directions, where the x and y directions are defined to be substantially parallel to said sample and the z direction is defined to be substantially perpendicular to said sample surface; x-direction control means, y-direction control means, and z-direction control means for applying respective signals to said x-direction driving means, said y-direction driving means, and said z-direction driving means, comprising the steps of: (a) producing a magnetic field alternating at said predetermined frequency to vibrate said tip by creating an interaction between said magnetic moment and said magnetic field, while scanning said tip along said sample surface and maintaining a distance between said tip and said sample surface such as to permit a tunneling current to flow to produce an alternating-magnetic-field-modulated scanned-surface-topography tunneling-current signal; (b) extracting from said alternating-magnetic-field-modulated scanned-surface-topography tunneling-current signal an alternating-magnetic-field-modulation component of said predetermined frequency; (c) eliminating from said alternating-magnetic-field-modulated scanned-surface-topography tunneling-current signal high-frequency components including said predetermined frequency to form a scanned-surface-topography tunneling-current signal component; and (d) determining the output of said z-direction control means so as to keep the scanned-surface-topography tunneling-current signal component essentially constant after removal of high-frequency components.

Claim 28

A method of observing a magnetic field near a surface of a sample that is conductive in at least said surface by using a scanning tunneling micros includes a cantilever and a tip supported by said cantilever, at least the surface of the end of said tip consisting of a magnetic material, comprising the steps of: (a) switching the direction of said magnetic moment of said tip at a predetermined frequency to vibrate said tip by creating interaction between said magnetic moment and said magnetic field while maintaining such a distance between said tip and said sample surface as to permit a tunneling current to flow; and (b) extracting a component of said predetermined frequency of said tunneling current, the component representing a measure of the magnetic field.

Claim 29

A method of observing a magnetic field near a surface of a sample that is conductive in at least said surface by using a scanning tunneling micros includes a cantilever and a tip supported by said cantilever, at least the surface of the end of said tip consisting of a magnetic material, comprising the steps of: (a) switching the direction of said magnetic moment of said tip at a predetermined frequency to vibrate said tip by creating interaction between said magnetic moment and said magnetic field while maintaining such a distance between said tip and said sample surface as to permit a tunneling current to flow; and (b) extracting a component of said predetermined frequency of said tunneling current, the component representing a measure of the magnetic field.

Claim 32

A method for simultaneously observing both the topography of a surface of a sample, which is conductive in at least said surface, and the magnetic field near the sample surface, using a scanning tunneling microscope that includes a cantilever; a tip supported by said cantilever, at least the surface of the end of said tip being made of a magnetic material; x-direction driving means, y-direction driving means, and z-direction driving means responsive to respective input signals for moving said tip in the x, y, and z directions, where the x and y directions are defined to be substantially parallel to said sample surface and the z direction is defined to be substantially perpendicular to said sample surface; and x-direction control means, y-direction control means, and z-direction control means for applying respective signals to said x-direction driving means, said y-direction driving means, and said z-direction driving means, comprising the steps of: (a) switching the direction of the magnetic moment of said tip at a predetermined frequency and vibrating said tip by creating an interaction between said magnetic moment and said magnetic field while scanning said tip along said sample surface and maintaining a distance between said tip and said sample surface such as to permit a tunneling current to flow to produce a magnetic-interaction-modulated scanned surface topography tunneling-current signal; (b) extracting from said magnetic-interaction-modulated scanned-surface-topography tunneling-current signal a magnetic-interaction modulation component of said predetermined frequency; (c) effectively eliminating from said magnetic-interaction-modulated scanned-surface-topography tunneling-current signal high-frequency components including said predetermined frequency to form a scanned-surface-topography tunneling-current signal component; and (d) determining the output of said z-direction control means so as to keep the scanned-surface-topography tunneling-current signal component essentially constant after removal of the high-frequency components.

Claim 33

A method for simultaneously observing both the topography of a surface of a sample, which is conductive in at least said surface, and the magnetic field near the sample surface, using a scanning tunneling microscope that includes a cantilever; a tip supported by said cantilever, at least the surface of the end of said tip being made of a magnetic material; x-direction driving means, y-direction driving means, and z-direction driving means responsive to respective input signals for moving said tip in the x, y, and z directions, where the x and y directions are defined to be substantially parallel to said sample surface and the z direction is defined to be substantially perpendicular to said sample surface; and x-direction control means, y-direction control means, and z-direction control means for applying respective signals to said x-direction driving means, said y-direction driving means, and said z-direction driving means, comprising the steps of: (a) switching the direction of the magnetic moment of said tip at a predetermined frequency and vibrating said tip by creating an interaction between said magnetic moment and said magnetic field while scanning said tip along said sample surface and maintaining a distance between said tip and said sample surface such as to permit a tunneling current to flow to produce a magnetic-interaction-modulated scanned surface topography tunneling-current signal; (b) extracting from said magnetic-interaction-modulated scanned-surface-topography tunneling-current signal a magnetic-interaction modulation component of said predetermined frequency; (c) effectively eliminating from said magnetic-interaction-modulated scanned-surface-topography tunneling-current signal high-frequency components including said predetermined frequency to form a scanned-surface-topography tunneling-current signal component; and (d) determining the output of said z-direction control means so as to keep the scanned-surface-topography tunneling-current signal component essentially constant after removal of the high-frequency components.