Enhancement of current-perpendicular-to-plane giant magnetoresistance by insertion of amorphous ferromagnetic underlayer in Heusler alloy-based spin-valve structures

We report an improved method for depositing Heusler alloy thin films, which reduces the B2-ordering temperature, and demonstrate its effect on improving spin-polarization and ΔR/R in CPP-GMR sensors. The insertion of a CoFeBTa or CoBTi amorphous ferromagnetic underlayer induced the formation of an amorphous Co2(Mn,Fe)Ge Heusler alloy film, reducing the B2-ordering temperature to ∼220 °C, which is significantly lower than the value of 500 °C for an epitaxial system and 400 °C for a polycrystalline system. This novel approach allows the fabrication of spin-valve sensor structures with ΔR/R of 18% after post-deposition annealing at temperatures less than 300 °C and is thus compatible with standard recording read-head sensor production.

[1]  J. Childress,et al.  Temperature-dependence of current-perpendicular-to-the-plane giant magnetoresistance spin-valves using Co2(Mn1−xFex)Ge Heusler alloys , 2016 .

[2]  K. Hono,et al.  Structure and magnetoresistive properties of current-perpendicular-to-plane pseudo-spin valves using polycrystalline Co2Fe-based Heusler alloy films , 2013 .

[3]  M. Shirai,et al.  Extensive study of giant magnetoresistance properties in half-metallic Co2(Fe,Mn)Si-based devices , 2012 .

[4]  M. Hayashi,et al.  Spin polarization and Gilbert damping of Co2Fe(GaxGe1−x) Heusler alloys , 2012 .

[5]  J. Katine,et al.  Co2MnGe-based current-perpendicular-to-the-plane giant-magnetoresistance spin-valve sensors for recording head applications , 2011 .

[6]  K. Hono,et al.  Large magnetoresistance in current-perpendicular-to-plane pseudospin valve using a Co2Fe(Ge0.5Ga0.5) Heusler alloy , 2011 .

[7]  K. Hono,et al.  Bulk and interfacial scatterings in current-perpendicular-to-plane giant magnetoresistance with Co2Fe(Al0.5Si0.5) Heusler alloy layers and Ag spacer , 2010 .

[8]  Xilin Peng,et al.  “All-Heusler alloy” current-perpendicular-to-plane giant magnetoresistance , 2009 .

[9]  S. Mitani,et al.  Large Interface Spin-Asymmetry and Magnetoresistance in Fully Epitaxial Co2MnSi/Ag/Co2MnSi Current-Perpendicular-to-Plane Magnetoresistive Devices , 2009 .

[10]  Keiichi Nagasaka,et al.  CPP-GMR technology for magnetic read heads of future high-density recording systems , 2009 .

[11]  N. Smith,et al.  All-Metal Current-Perpendicular-to-Plane Giant Magnetoresistance Sensors for Narrow-Track Magnetic Recording , 2008, IEEE Transactions on Magnetics.

[12]  K. Tsunekawa,et al.  Transmission electron microscopy study on the polycrystalline CoFeB∕MgO∕CoFeB based magnetic tunnel junction showing a high tunneling magnetoresistance, predicted in single crystal magnetic tunnel junction , 2007 .

[13]  S. Yuasa,et al.  Characterization of growth and crystallization processes in CoFeB /MgO/CoFeB magnetic tunnel junction structure by reflective high-energy electron diffraction , 2005 .

[14]  K. Hono,et al.  On low-temperature ordering of FePt films , 2005 .

[15]  Hitoshi Iwasaki,et al.  The applicability of CPP-GMR heads for magnetic recording , 2002 .

[16]  B. Das,et al.  Growth and magnetic properties of single crystal Co/sub 2/MnX (X=Si,Ge) Heusler alloys , 2001 .