Magnetic recording device and magnetic recording method utilizing assisted magnetic recording

A magnetic recording device, comprising:

• a magnetic head including a first magnetic pole, a second magnetic pole, a magnetic element, and a coil, the magnetic element being located between the first magnetic pole and the second magnetic pole, the magnetic element including a first magnetic layer;
• a first circuit configured to supply a coil current to the coil;
• a second circuit configured to supply an element current to the magnetic element;
• a third circuit configured to detect an electrical resistance of the magnetic element;
• and
• a controller configured to control the element current by controlling the second circuit based on the electrical resistance detected by the third circuit,
• wherein
• the coil current is an alternating current that includes a first frequency,
• the third circuit detects an electrical signal obtained from the magnetic element,
• the electrical signal includes a second frequency that is 2 times the first frequency, and
• the electrical resistance corresponds to a temporal average of the electrical signal.

A magnetic recording device, comprising:

• a magnetic head including a first magnetic pole, a second magnetic pole, a magnetic element, and a coil,
• the magnetic element being located between the first magnetic pole and the second magnetic pole,
• the magnetic element including
• a first magnetic layer,
• a first magnetic pole-side nonmagnetic layer located between the first magnetic pole and the first magnetic layer, and
• a second magnetic pole-side nonmagnetic layer located between the first magnetic layer and the second magnetic pole,
• the first magnetic pole-side nonmagnetic layer including one of a first material or a second material,
• the second magnetic pole-side nonmagnetic layer including the other of the first material or the second material,
• the first material including at least one selected from the group consisting of Ta, Pt, W, Ir, Mo, Cr, Tb, Mn, and Ni,
• the second material including at least one selected from the group consisting of Cu, Ag, Au, Cr, and Ru;
• a first circuit configured to supply a coil current to the coil;
• and
• a second circuit configured to supply an element current to the magnetic element,
• a polarity of the coil current changing at a first time,
• the second circuit setting the element current to a first value before a second time,
• the second circuit changing the element current to a second value at the second time, the second value being different from the first value,
• the second circuit changing the element current to the first value at a third timed after the second time.

A magnetic recording device, comprising:

• a magnetic head including a first magnetic pole, a second magnetic pole, a magnetic element, and a coil,
• the magnetic element being located between the first magnetic pole and the second magnetic pole,
• the magnetic element including
• a first magnetic layer,
• a second magnetic layer located between the first magnetic layer and the first magnetic pole,
• a first nonmagnetic layer located between the first magnetic layer and the second magnetic layer,
• a first magnetic pole-side nonmagnetic layer located between the first magnetic pole and the second magnetic layer, and
• a second magnetic pole-side nonmagnetic layer located between the first magnetic layer and the second magnetic pole;
• a first circuit configured to supply a coil current to the coil;
• and
• a second circuit configured to supply an element current to the magnetic element,
• a polarity of the coil current changing at a first time,
• the second circuit setting the element current to a first value before a second time,
• the second circuit changing the element current to a second value at the second time,
• the second value being different from the first value,
• the second circuit changing the element current to the first value at a third time after the second time,
• the second circuit changing the element current to a third value at a fourth time before the second time,
• the third value being different from the first value and different from the second value,
• the second circuit changing the element current toward the second value at a fifth time after the fourth time and at or before the second time.