Thermal Stability Study of Tilted-Polarizer Spin Torque Nano-oscillator

The spin torque nano-oscillator (STNO) with out of film plane fixed layer magnetization, namely the tilted-polarizer spin torque nano-oscillator (TP-STNO), has the advantage of microwave generation without the help of a magnetic field, which makes it promising to be integrated into a chip. In this paper, we present a thermal stability study of TP-STNO by macrospin modeling, in which the thermal noise is induced into the H eff of the Landau-Liftshitz-Gilbert-Slonczewski equation in the form of a stochastic magnetic field. The TP-STNO with different tilted angles is studied by numerical simulations based on the macrospin model and nonlinear system theory. Depending on the analysis of Lyapunov exponents as a function of drive current density in the room temperature range, we obtain the drive current density ranges in which TP-STNO can oscillate stably in the presence of thermal noise. These quantified results are essential during the practical usage of TP-STNO.