Magnetoresistive switch effect in MnSb granular films grown on sulfur-passivated GaAs: more-than 10 000% magnetoresistance effect at room-temperature

A huge positive magnetoresistance effect, more than 10000% at room temperature, has been discovered in MnSb granular films. Granular films consisting of nanoscale MnSb dots were fabricated on a sulfur-passivated GaAs (001) substrate by molecular-beam epitaxy, then covered with an Sb thin layer. The MnSb granular films exhibit a strong in-plane anisotropy of the magnetic-field-sensitive current–voltage characteristics. When a constant voltage, above the threshold value, is applied in the [110] direction of the GaAs (001) surface, a steep change in the current, which we term magnetoresistive switch (MRS), is driven by the huge magnetoresistance effect under a relatively low magnetic field (less than about View the MathML source). On the other hand, less than 1% magnetoresistance effect was observed when the voltage was applied in the View the MathML source direction of the GaAs surface. The origin of the anisotropy is discussed in terms of the microscopic structural anisotropy at the heterointerface.