Thermomagnetic analog recording

Both coercivity and saturation magnetization of a CrO2decrease with increasing temperature and the remanent magnetization determined by a small magnetic field at a temperature near the Curie point increases sufficiently when it cools down to room temperature. A new thermomagnetic recording method of an analog signal on a CrO2tape was tried by using a conventional magnetic head and a laser beam as a heating source. Recording is achieved by locally raising the temperature of the tape and applying simultaneously a small magnetic field which varies with the input signal. A conventional magnetic head was used for reproduction. From the result of a series of experiments, it can be concluded that this new recording method has the following characteristics. 1) Liberation of heat makes it possible to record the signal by a small magnetic field. 2) In spite of no-bias recording the reproduced output is linearly proportional to the recording current. 3) This method can be used for fairly high density analog recording (track width 20 μm, recording wavelength 10 μm).