Program Highlights

Robust Isothermal Electric Control of Exchange Bias
at Room Temperature

Ch. Binek, P. Dowben, and K. D. Belashchenko
Nebraska MRSEC

Spintronics exploits the spin degree of freedom of electrons to create an advanced generation of electronic devices with reduced power consumption and enhanced processing speed, integration density, and functionality in comparison with present day CMOS electronics. Almost all existing and prototypical solid-state spintronic devices rely on tailored interface magnetism, enabling spin-selective transmission or scattering of electrons. Hence, controlling interface magnetism is a key challenge to better spintronics and a major research thrust of the Nebraska MRSEC. IRG2 researchers achieved experimental and theoretical evidence of a roughness-insensitive and electrically controllable ferromagnetic state at a specific surface of chromia (see figure). When placed in atomic proximity with a ferromagnetic Co/Pd film, quantum mechanical exchange induces a shift of the Co/Pd hysteresis along the magnetic field axis known as exchange bias effect. Our Cr₂O₃/CoPd heterostructure allows for reversible, isothermal and global switching of the exchange bias field by electric means. These results promise a new route towards voltage-controlled spintronics and electrically control magnetism.

This research is supported by the National Science Foundation, Division of Materials Research, Materials Research Sciences and Engineering Program, Grant 0820521.

Isothermal electric switching of exchange bias in Cr₂O₃/CoPd at room temperature. Crystal structures of chromia represent the two magnetoelectric switchable antiferromagnetic domains and their roughness insensitive surface FM state.