17:15 〜 17:30
▼ [5p-C18-15] Voltage controlled magnetic anisotropy of monoatomic Pt layer at Fe/MgO interface characterized by X-ray absorption spectroscopy
キーワード：X-ray magnetic circular dichroism, Voltage controlled magnetic anisotropy
In order to control the magnetization direction in nanomagnets for magetoresistive random access memory (MRAM), voltage controlled magnetic anisotropy (VCMA) in ferromagnetic metal is a candidate. However, it is necessary to enhance VCMA for application. Recently, in L10-FePt/MgO system, it has been reported that voltage induction of not only orbital magnetic moment but also magnetic dipole moment (Tz term) drastically changes the magnetic anisotropy. In the present study, we report Fe/Pt/MgO system in which Pt monoatomic layer is located at the Fe/MgO interface for further investigation.
MgO(001) substrate/MgO (5 nm)/V(30 nm)/Fe(0.5 nm)/Pt (0.2 nm)/MgO(2 nm) multilayer was fabricated by molecular beam epitaxy. After that, 5 nm-SiO2 was deposited by sputtering. Then 2 nm-Cr and 5 nm-Pd were deposited. The multilayer was patterned into tunnel junctions whose size was 80 µm in a diameter. To investigate electronic and magnetic properties of Pt, X-ray absorption spectroscopy and its X-ray magnetic circular dichroism (XMCD) were conducted at BL39XU at SPring-8. From magnetization hysteresis under external voltages of ±2.6V (±0.18 V/nm), VCMA in the system was estimated to be 140 fJ/Vm. Voltage induced lattice relaxation around Pt atom and induced XMCD change will be discussed.
MgO(001) substrate/MgO (5 nm)/V(30 nm)/Fe(0.5 nm)/Pt (0.2 nm)/MgO(2 nm) multilayer was fabricated by molecular beam epitaxy. After that, 5 nm-SiO2 was deposited by sputtering. Then 2 nm-Cr and 5 nm-Pd were deposited. The multilayer was patterned into tunnel junctions whose size was 80 µm in a diameter. To investigate electronic and magnetic properties of Pt, X-ray absorption spectroscopy and its X-ray magnetic circular dichroism (XMCD) were conducted at BL39XU at SPring-8. From magnetization hysteresis under external voltages of ±2.6V (±0.18 V/nm), VCMA in the system was estimated to be 140 fJ/Vm. Voltage induced lattice relaxation around Pt atom and induced XMCD change will be discussed.