Spin Precession in Oblique Magnetic Fields

The authors have measured spin precession from devices with 350 micron-thick undoped silicon transport layers in an oblique magnetic field synthesized by a static magnetic field B_par and a varied magnetic field B_perp. Experimental results of spin precession, measured by changing the fixed in-plane magnetic field magnitude at zero device misalignment are also presented. Repeating this study at a fixed device misalignment angle of 30 degrees is also shown as is holding the fixed field constant at different misalignment angles is shown . The authors modeled the device spin detector current using a drift-diffusion model which in linear response is proportional to the projection of final spin direction (after transport) on the measurement axis determined by detector magnetization. Under the influence of an oblique magnetic field, spin is induced to precess around the magnetic field, which produces asymmetric Hanle curves (due to broken symmetry of spin direction or spin precession chirality, or both) that are different from those measured in single-axis magnetic fields. The simulated spin precession measurements are presented and compared favorably to the experimental data . In conclusion, the Hanle spin precession signal is suppressed when a fixed in-plane magnetic field is used in conjunction with a varied magnetic field perpendicular to the plane of the spin-transport device, and the signal becomes asymmetric when the device is misaligned with respect to magnetic fields.