Magnetic recording and reproducing device

A magnetic recording and reproducing device comprising:

• a rotatable disk-shaped recording medium including a magnetic recording layer;
• and
• a magnetic recording head which records information on the recording medium and comprises:
• an air bearing surface;
• a main magnetic pole which has a distal end portion extending to the air bearing surface and generates a perpendicular recording magnetic field;
• an auxiliary magnetic pole which faces the distal end portion of the main magnetic pole across a write gap and constitutes a magnetic core with the main magnetic pole;
• a magnetic flux control layer which includes a first conductive layer provided on the main magnetic pole, an adjustment layer provided on the first conductive layer and formed of a magnetic material comprising one of iron, cobalt or nickel, and a second conductive layer electrically connecting the adjustment layer and the auxiliary magnetic pole, and generates a spin torque and inverts a direction of magnetization in the adjustment layer, when current is supplied;
• and
• a protective layer which is provided on the air bearing surfaces of the main magnetic pole, the magnetic flux control layer and the auxiliary magnetic pole, wherein
• a voltage Vb applied to the magnetic control layer is lower than a voltage Vba represented by an expression (1)
• Vba=Vb0−a×1/log(t)×log(RH)×log(PO2) (1)
• where Vb0 is a maximum voltage applicable to the magnetic flux control layer, t is a thickness (nm) of the protective film, RH is a relative humidity, PO2 is an oxygen partial pressure (Pa) of an atmosphere in the device, and a is a coefficient of the device.