According to one embodiment, a magnetic recording device includes a magnetic head and a controller. The magnetic head includes a first magnetic pole, a magnetic element including a first magnetic layer, and a coil. The controller is electrically connected to the magnetic element and the coil. The controller is configured to supply a recording current to the coil and supply an element current to the magnetic element. The recording current includes a first period of a first polarity, a second period of a second polarity, a third period that shifts from the first to second period, and a fourth period that shifts from the second to first period. The element current includes DC and AC components. The AC component in the first period is the same as the AC component in the second period, the AC component in the third period, and the AC component in the fourth period.

A hexagonal strontium ferrite powder, in which an average particle size is 10.0 to 25.0 nm, a content of one or more kinds of atom selected from the group consisting of a gallium atom, a scandium atom, an indium atom, and an antimony atom is 1.0 to 15.0 atom % with respect to 100.0 atom % of an iron atom, and a coercivity Hc is greater than 2,000 Oe and smaller than 4.000 Oe. A magnetic recording medium including: a non-magnetic support; and a magnetic layer including a ferromagnetic powder and a binding agent on the non-magnetic support, in which the ferromagnetic powder is the hexagonal strontium ferrite powder. A magnetic recording and reproducing apparatus including this magnetic recording medium.

A magnetic recording medium is a tape-shaped magnetic recording medium that has a recording layer including an ε-iron oxide particle. An area ratio R.sub.low (=(S.sub.low/S.sub.total)×100) of a total area S.sub.total of an SFD curve of the recording layer in a perpendicular direction and an area S.sub.low of the SFD curve in which a coercivity Hc is in a range from −500 [Oe]≤Hc≤500 [Oe] is equal to or less than 5.5%.

Magnetic recording media including a soft magnetic underlayer (SUL) formed over a plasma-polished substrate or pre-seed layer. In some examples, the substrate or pre-seed layer is plasma-polished using an inert gas such as krypton so that the roughness of the surface on which the SUL is deposited is reduced. The roughness reduction can lead to improved crystallographic texture within subsequently deposited media films, and consequently, to increased recording performance of the media. In particular, media signal-to-noise ratio (SNR), linear recording density, and areal recording density or areal density capacity (ADC) can be improved. In one aspect, a carbon deposition/etching apparatus may be modified to polish the substrate or pre-seed layer with krypton or other inert gases, rather than be used to deposit carbon overcoat.

A magnetic tape in which an arithmetic average roughness Ra measured at a surface of the magnetic layer with an atomic force microscope is 2.0 nm or less, and in an environment with a temperature of 23° C. and a relative humidity of 50%, an AlFeSil abrasion value.sub.45° of a surface of the magnetic layer measured at a tilt angle of 45° of an AlFeSil prism is 20 μm to 50 μm, a standard deviation of an AlFeSil abrasion value of the surface of the magnetic layer measured at each of tilt angles of 0°, 15°, 30°, and 45° of the AlFeSil prism is 30 μm or less, and the tilt angle of the AlFeSil prism is an angle formed by a longitudinal direction of the AlFeSil prism and a width direction of the magnetic tape.

A magnetic recording medium includes a substrate, a soft magnetic underlayer on the substrate, and a dual seed layer. The dual seed layer includes a first seed layer comprising NiFe at a first concentration, and a second seed layer comprising NiFe at a second concentration different from the first concentration and a segregant. The first seed layer may be on a soft magnetic underlayer and the second seed layer is on the first seed layer. The magnetic recording medium may further include one or more magnetic recording layers on the dual seed layer. The magnetic recording medium with the composition-graded dual seed layer may provide small grain size and good crystallographic texture for layers on the dual seed layer, including the magnetic recording layers.

The magnetic recording medium includes a non-magnetic support; and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, in which an isoelectric point of a surface zeta potential of the magnetic layer is equal to or greater than 5.5.

According to one embodiment, a magnetic recording device includes a magnetic head and a controller. The magnetic head includes a first magnetic pole, a magnetic element including a first magnetic layer, and a coil. The controller is electrically connected to the magnetic element and the coil. The controller is configured to supply a recording current to the coil and supply an element current to the magnetic element. The recording current includes a first period of a first polarity, a second period of a second polarity, a third period that shifts from the first to second period, and a fourth period that shifts from the second to first period. The element current includes DC and AC components. The AC component in the first period is the same as the AC component in the second period, the AC component in the third period, and the AC component in the fourth period.

A magnetic tape in which an arithmetic average roughness Ra measured at a surface of a magnetic layer with an atomic force microscope is 2.0 nm or less, and in an environment with a temperature of 32° C. and a relative humidity of 80%, a frictional force F.sub.45° on the surface of the magnetic layer with respect to an LTO8 head measured at a head tilt angle of 45° is 4 gf to 15 gf, and a standard deviation of a frictional force F on the surface of the magnetic layer with respect to the LTO8 head measured at each of head tilt angles of 0°, 15°, 30°, and 45° is 10 gf or less.

The magnetic recording medium includes at least a nonmagnetic substrate and a magnetic recording layer, the magnetic recording layer consists of a first magnetic recording layer or a plurality of layers including at least the first magnetic recording layer and a second magnetic recording layer, the first magnetic recording layer has a granular structure including a first magnetic crystal grain and a first nonmagnetic crystal grain boundary, the first magnetic crystal grain consists of an ordered alloy having Fe, Pt and Rh, the first nonmagnetic crystal grain boundary consists of carbon, boron or a combination thereof, the second magnetic recording layer has a granular structure including a second magnetic crystal grain and a second nonmagnetic crystal grain boundary, the second magnetic crystal grain consists of an FePt ordered alloy or an ordered alloy having Fe, Pt and Rh, and the second nonmagnetic crystal grain boundary includes carbon.