Electric field induced reversible 180° magnetization switching through tuning of interfacial exchange bias along magnetic easy-axis in multiferroic laminates

Abstract

E-field control of interfacial exchange coupling and deterministic switching of magnetization have been demonstrated in two sets of ferromagnetic(FM)/antiferromagnetic(AFM)/ferroelectric(FE) multiferroic heterostructures, including NiFe/NiCoO/glass/PZN-PT (011) and NiFe/FeMn/glass/PZN-PT (011). We designed this experiment to achieve exchange bias tuning along the magnetic easy axis, which is critical for realizing reversible 180° magnetization deterministic switching at zero or small magnetic bias. Strong exchange coupling were established across AFM-FM interfaces, which plays an important role in voltage control of magnetization switching. Through the competition between the E-field induced uniaxial anisotropy in ferromagnetic layer and unidirectional anisotropy in antiferromagnetic layer, the exchange bias was significantly shifted by up to |∆Hex|/Hex = 8% in NiFe/FeMn/glass/PZN-PT (011) and 13% in NiFe/NiCoO/glass/PZN-PT (011). In addition, the square shape of the hysteresis loop, as well as a strong shape tunability of |∆Hex|/Hc = 67.5 ~ 125% in NiFe/FeMn/glass/PZN-PT and 30 ~ 38% in NiFe/NiCoO/glass/PZN-PT were achieved, which lead to a near 180° magnetization switching. Electrical tuning of interfacial exchange coupling in FM/AFM/FE systems paves a new way for realizing magnetoelectric random access memories and other memory technologies.

Recent progress in voltage control of magnetism: Materials, mechanisms, and performance

“…A similar result was also reported by Xue et al [327] and it implies that AFM/FM/FE multiferroic heterostructures are prototypes to tune exchange coupling by electric fields and constitute an important step toward a practical MRAM at room temperature.…”

“…However, it is a great challenge to break the limits of 90° switching magnetization without the assistance of a magnetic field or spin-transfer torque. An alternative method to replace the external magnetic field is the introduction of an electric field [327,328]. The manipulation of magnetization reversal by a pure electric field rather than a magnetic field has been reported by some groups [51,52,59], which illuminates the direction of magnetic field-free switching in the future.…”

Status and Perspectives of Multiferroic Magnetoelectric Composite Materials and Applications

“…Heron et al [116] approached this issue through E-field control of exchange bias in multiferroic/magnetic (CoFe/BiFeO 3 ) heterostructures. Xue et al [117] demonstrated that the E-field induced near 180˝magnetization switching in the AFM/FM/FE heterostructures through voltage-controlled tuning of exchange bias and through manipulation of coercive fields. The irreversibility of the E-field induced near 180˝magnetization switching in AFM/FM/FE heterostructures was resolved by employing a magnetic impulse, which could switch the magnetization back and lead to a continuous magnetization switching [118].…”

Complex Study of Magnetization Reversal Mechanisms of FeNi/FeMn Bilayers Depending on Growth Conditions

“…Figure 3 shows diffractograms of the films deposited at substrate temperatures of 17, 100, 200, 400, 500, and 600 °C. The XRD patterns show peaks corresponding to the FeMn and NiFe layers to have the fcc structure with (111) orientation that is usually observed in such structures [ 28 , 29 , 30 , 31 ]. Moreover, one can see that the peak intensity of the FeMn layer decreases with the increasing substrate temperature, while the width of the FeMn peaks increases with the increasing T SUB .…”