Thin, horizontal-plane Hall sensors for read heads in magnetic recording

We show that thin mesoscopic: read-head sensors with a vertical resolution of similar to 30 nm are advantageous far detecting magnetic fields from high-density recording media and compare such sensors constructed from narrow-gap semiconductors using the Hall bar and Corbino (giant magnetoresistance) geometries. For signal fields below a critical crossover field similar to 0.5 T, the Hall bar yields a larger output voltage. The maximum output voltage for a thin Hall bar detector is proportional to the maximum drift velocity of the sensor material and to its width. The maximum output voltage and power signal-to-noise ratios are calculated for thin Hall bar read-head sensors constructed from a number of polar semiconductor materials. Read heads of this type are shown to be competitive with metallic spin valve magnetoresistive read heads. We propose a simple, commercially practical procedure for the fabrication of thin Hall bar read-head sensors with high sensitivity and high spatial resolution.