Patent ID: 7268563
Filing Date: 2007-09-11
Classification: G01R

Abstract:
1. A point contact probe for measuring spin polarization of a sample, comprising: an elongate tube; a vacuum-sealed housing mounted to said elongate tube near a proximal end thereof; said vacuum-sealed housing adapted for connection to a temperature and magnetic field control apparatus; said temperature and magnetic field control apparatus being a physical property measurement system; said vacuum-sealed housing also adapted for electrical connection to a sourcemeter and a voltmeter; a sample housing secured to said tube near a distal end thereof; a tip holder mounted within said sample housing; a superconducting tip extending from a distal end of said tip holder; said superconducting tip being in electrical communication with said physical property measurement system; a sample holder secured to a distal end of said sample housing: said sample holder adapted to hold a sample; control means for controlling a distance between said sample and said superconducting tip; said control means adapted to retract and extend said superconducting tip away from and toward, said sample, respectively; said control means including a rotatably mounted coarse control knob positioned at a proximal end of said elongate tube; said rotatably mounted coarse control knob being formed integrally with a coarse adjustment rod so that rotation of said coarse control knob in a first rotational direction effects simultaneous and corresponding rotation of said coarse adjustment rod in said first rotational direction and so that rotation of said coarse control knob in a second rotational direction opposite to said first rotational direction effects simultaneous and corresponding rotation of said coarse adjustment rod in said second rotational direction; said control means further including a differential micrometer; said differential micrometer including a shaft having a diameter-reducing annular shoulder formed therein that divides a first, large diameter proximal section of said shaft from a second, reduced diameter distal section of said shaft; said proximal section of said shaft being externally threaded and having a first preselected number of threads per unit length formed therein; said distal section of said shaft being externally threaded and having a second preselected number of threads per unit length formed therein; an internally threaded slider in screw-threaded engagement with said proximal section of said shaft; an internally threaded sleeve in screw-threaded engagement with said distal section of said shaft; said tip holder mounted to a distal end of said internally threaded sleeve; a micrometer rod disposed in axial alignment with said coarse adjustment rod: a distal end of said coarse adjustment rod disposed in abutting relation to a proximal end of said micrometer rod; clamp means for securing together said coarse adjustment rod and said micrometer rod; said differential micrometer including an internally threaded boss that screw threadedly engages said coarse adjustment rod; whereby rotation of said coarse adjustment rod in said first rotational direction causes said coarse adjustment rod to advance in a first linear direction and to bear against said micrometer rod and to displace said micrometer rod and hence said differential micrometer and said tip holder in said first linear direction; and whereby rotation of said coarse adjustment rod in said second rotational direction causes said coarse adjustment rod to displace in a second liner direction opposite from said first linear direction and to displace said micrometer rod and hence said differential micrometer and said tip holder in said second linear direction; said control means further including a fine adjustment knob secured to a proximal end of said coarse adjustment rod; an elongate slot formed in said internally threaded slider; a setscrew opening formed in said sample housing; a setscrew that extends through said opening and into said elongate slot to prevent rotation of said slider; said setscrew bearing against a first side of said elongate slot when said fine adjustment knob is abruptly rotated in a first rotational direction so that continued rotation of said fine adjustment knob in said first rotational direction causes said differential micrometer to rotate in said first rotational direction relative to said internally threaded slider and to travel in a first linear direction; said setscrew bearing against a second side of said elongate slot when said fine adjustment knob is abruptly rotated in a second rotational direction opposite to said first rotational direction so that continued rotation of said fine adjustment knob in said second rotational direction causes said differential micrometer to route in said second rotational direction relative to said internally threaded slider and to travel in a second linear direction opposite to said first linear direction; said linear travel in said first direction of said differential micrometer causing said internally threaded sleeve and hence said tip holder to travel in a first linear direction toward said sample; and said linear travel in said second direction of said differential micrometer causing said internally threaded sleeve and hence said tip holder to travel in a second linear direction away from said sample.