To understand the spin-torque effect on the noise in tunneling magnetoresistive (TMR) read heads, the GHz range noise spectra of TMR read heads with a narrow track width (w-=-36-nm), and various stripe heights (h) are investigated as a function of the external magnetic field (Hex) and dc bias current density (j). The strong noise peak intensity depends on both Hex and j, indicating that the spin-torque affects the thermal mag-noise under a positive (negative) j for a positive (negative) Hex, regardless of h in the TMR heads. Due to the increased shape anisotropy, the critical current density (jc), where the non-thermal fluctuation noise originates from the spin-torque, increases markedly as the head dimension is reduced, and the maximum value of jc is approximately +1.5-×-1012-A/m2 for a head with w-=-36-nm and h-=-15-nm. These results demonstrate that the non-thermal fluctuation noise originating from the spin-torque in the TMR head can be suppressed in the current density range below 1012-A/m2, as the head dimension is reduced and the shape anisotropy is increased.
ASJC Scopus subject areas
- Physics and Astronomy(all)