1. 1) Y. Martin and H. K. Wickramasinghe: Appl. Phys. Lett. 50 (1987) 1455–1457.
2. 2) Y. Martin, D. W. Abraham and H. K. Wickramasinghe: Appl. Phys. Lett. 52 (1988) 1103–1105.
3. 3) With scanning movement of the piezoelectric tube, mechanical vibration occurs. The eigen frequencies of the tip edges yield to the shape of them. In the case of normal STM tip shape, the eigen frequency is low, because of small moment of inertia of area. In the case of the round tip, the eigen frequency is high. The round tip is not easy to vibrate mechanically.
4. 4) The polycrystalline iron tip magnetrostriction, Δl is roughly estimated to be 0.4 nm from the next equation, Δl=λsl, where l is the length of the solenoid coil and λs=2λ100⁄5+3λ111⁄5 is the coefficient of the magnetostriction of polycrystalline. The anisotropic coefficients of the magnetostriction, λ100 and λ111 are also 0.1×10−6 in the magnetic field of 0.05 T . The value is not negligible taking into account of 0.9 nm tunnel gap. The vibration due to the magnetostriction must be solved to atomic resolution. The vibration did not influence upon the measurement of mutual inductance, because the tunnel gap is feedback controlled by the tunnel current.
5. 5) The magnetic permeability of the iron needle tip, μ is assumed to be 2000. The intensity of magnetic field in the iron needle of the coil is calculated from the equation, H=nI(cosθ2−cosθ1)⁄2, where n is the turn number of the coil, I is the electric current, θ1 is the angle between the axis of the coil and the segment from a starting point of the coil to the center on the axis of coil, the angle θ2 from the endpoint of the coil is defined same as above.