In-plane magnetized film, in-plane magnetized film multilayer structure, hard bias layer, magnetoresistance effect element, and sputtering target

An in-plane magnetized film multilayer structure for use as a hard bias layer of a magnetoresistive effect element, the in-plane magnetized film multilayer structure comprising:

• a plurality of in-plane magnetized films;
• and
• a nonmagnetic intermediate layer a crystal structure of which is a hexagonal closest packed structure, wherein
• the nonmagnetic intermediate layer is disposed between the in-plane magnetized films, and the in-plane magnetized films adjacent across the nonmagnetic intermediate layer are coupled by a ferromagnetic coupling,
• each of the in-plane magnetized films
• contains metal Co, metal Pt, and an oxide,
• contains the metal Co in an amount of 45 at% or more and 80 at% or less and the metal Pt in an amount of 20 at% or more and 55 at% or less relative to a total of metal components of the each of the in-plane magnetized film, and
• contains the oxide in an amount of 3 vol% or more and 25 vol% or less relative to a whole amount of the each of the in-plane magnetized film,
• an in-plane direction average grain diameter of magnetic crystal grains of the in-plane magnetized film is 15 nm or more and 30 nm or less, and
• a total thickness of the plurality of in-plane magnetized films is 20 nm or more.

An in-plane magnetized film multilayer structure for use as a hard bias layer of a magnetoresistive effect element, the in-plane magnetized film multilayer structure comprising:

• a plurality of in-plane magnetized films;
• and
• a nonmagnetic intermediate layer, wherein
• the nonmagnetic intermediate layer is disposed between the in-plane magnetized films, and the in-plane magnetized films adjacent across the nonmagnetic intermediate layer are coupled by a ferromagnetic coupling,
• each of the in-plane magnetized films
• contains metal Co, metal Pt, and an oxide,
• contains the metal Co in an amount of 45 at% or more and 80 at% or less and the metal Pt in an amount of 20 at% or more and 55 at% or less relative to a total of metal components of the each of the in-plane magnetized films, and
• contains the oxide in an amount of 3 vol% or more and 25 vol% or less relative to a whole amount of the each of the in-plane magnetized films,
• an in-plane direction average grain diameter of magnetic crystal grains of the each of the in-plane magnetized films is 15 nm or more and 30 nm or less, and
• the in-plane magnetized film multilayer structure has a magnetic coercive force of 2.00 kOe or more and remanent magnetization per unit area of 2.00 memu/cm2 or more.

A sputtering target for use in forming an in-plane magnetized film for use as at least part of a hard bias layer of a magnetoresistive effect element by room temperature film formation, wherein

• the sputtering target
• contains metal Co, metal Pt, and an oxide,
• contains the metal Co in an amount of 50 at% or more and 85 at% or less and the metal Pt in an amount of 15 at% or more and 50 at% or less relative to a total of metal components of the sputtering target, and
• contains the oxide in an amount of 3 vol% or more and 25 vol% or less relative to a whole amount of the sputtering target, and
• the in-plane magnetized film to be formed has a magnetic coercive force of 2.00 kOe or more and remanent magnetization per unit area of 2.00 memu/cm2 or more.