Experimental studies using in-contact recording on chromium-cobalt films

Cr-Co evaporated films were written upon and read with a vibrating head apparatus. The effects of the head-to-medium spacing upon the half-pulsewidth were carefully measured between 0 and 4 μm. The formula
P_{50} = [g^{2} + 4(d + a)^{2}]^{1/2}
was found to hold quite well. However, the conservation of P
50
after the heating of a recording and the consequent increase of
tB_{r}/H_{c}
raise questions about the effect of the self-demagnetization outside the head, usually assumed as dominant.