Dynamical stability by spin transfer in nearly isotropic magnets

Area of Science:

• Spintronics
• Condensed Matter Physics
• Materials Science

Background:

• Spin transfer torques (STTs) are crucial for controlling magnetization in spintronic devices using electric currents.
• STTs counteract magnetic relaxation, enabling manipulation of magnetic states.
• Developing materials with tailored magnetic properties is key for advancing spintronic applications.

Purpose of the Study:

• To maximize the spin transfer torque effect in CoFeB thin films.
• To investigate the dynamical stabilization of magnetization in nearly isotropic magnetic systems.
• To explore the potential of STT-driven magnetization dynamics for probabilistic computing and neuromorphic hardware.

Main Methods:

• A dedicated growth-annealing protocol was employed to create CoFeB thin films.
• Magnetic anisotropies (interface and shape) were engineered to nearly cancel each other, resulting in isotropic magnets.
• The behavior of magnetization under varying current regimes was studied, including dynamical stabilization and large fluctuations.

Main Results:

• Nearly isotropic CoFeB magnets were successfully fabricated, exhibiting near cancellation of magnetic anisotropies.
• Low-current dynamical stabilization of magnetization opposite to an applied magnetic field was achieved, analogous to the Kapitza pendulum.
• STTs were shown to drive extensive magnetization vector fluctuations across the entire Bloch sphere in an intermediate current regime.

Conclusions:

• Isotropic magnets provide a novel platform for exploring far-from-equilibrium spin dynamics, including anti-magnonics.
• The stochastic nature of magnetization direction under STT can be harnessed as a resource for probabilistic computing and neuromorphic applications.
• This work opens new avenues for unconventional computing paradigms leveraging advanced spintronic phenomena.