Model of a tunnel point contact as an orifice in an interface that is nontransparent for electrons except for a circular hole, where tunneling is allowed. Trajectories are shown schematically for electrons that are reflected from or transmitted through the contact and then scattered back by a defect.
Spatial distribution of the square of the modulus of the wave function in the vicinity of a contact in a plane perpendicular to the interface passing through the contact and a defect. Distances are given in units of the inverse wave number.47
Dependence of the normalized oscillatory part of the conductance on the STM tip position for different depths of the defect below the surface; , .
Dependence of the oscillatory part of the conductance, , as a function of the position of a defect in the plane . The shape of the FS (41) is defined by the mass ratios , , and the long axis of the ellipsoid is rotated by about the x axis, away from the y axis. The coordinates are measured in units of (46) and the defect lies at .51
(a) The Fermi surface given by Eq. (48) relative to the contact axis for three principal lattice orientations. (b) A plot of the tunneling point-contact conductance G as a function of the contact position for a defect at the origin, at a depth of and for a (100) surface plane; the x and y directions each correspond to 100 directions. (c) Same plot for a (111) surface orientation; the x and y directions correspond to and directions, respectively. (d) Same plot for a (110) surface orientation; the x and y directions correspond to  and directions, respectively.69
The difference between the conductance as a function of voltage for a magnetic and a nonmagnetic impurity. The parameters , , and are used in Eq. (49) and (46).
The oscillatory part of the conductance as a function of tip position on a metal surface for subsurface magnetic clusters with different cluster diameters. The -coordinate is measured from the point at which the contact is situated directly above the cluster; ; ; ; ; .64
Schematic representation of the electron trajectories in the vicinity of a point contact in an external magnetic field oriented along the contact axis.
Oscillatory part of the conductance of a tunneling point contact with a single defect placed at , . The solid curve is a plot of Eq. (62), while the dashed curve shows the component in the semiclassical approximation (68). The field scale is given in units of , and .
The oscillatory part of the STM conductance as a function of tip position for different values of magnetic field; , and .
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