研究目的
To investigate the dependence of voltage-controlled magnetic anisotropy (VCMA) effect and its volatility on the underlayer in CoFeB/MgO structures.
研究成果
The volatility of the VCMA effect depends on the underlayer material: non-volatile for Ta or Pt ULs with a critical gate voltage threshold, and volatile for W UL with linear dependence. By using a Ta/W bilayer UL, the volatility can be controlled, allowing arbitrary modulation of magnetic properties. This enables multi-level magnetic states and has implications for energy-efficient spintronic devices.
研究不足
The study does not fully verify the underlying physical mechanisms for the observed volatility differences, such as crystal structure differences, built-in strain, or oxygen diffusion coefficients. Further theoretical and experimental studies are needed to confirm these scenarios. The use of ZrO2 as gate oxide may have limitations in ion mobility compared to other oxides.
1：Experimental Design and Method Selection:
The study investigates the VCMA effect in UL/CoFeB/MgO/AlOx structures with different underlayers (Ta, Pt, W, Ta/W bilayer) to understand the volatility and dependence on UL materials. Magnetron sputtering is used for deposition, and transport measurements are conducted using a Hall bar structure with a gate voltage applied.
2：Sample Selection and Data Sources:
Samples are deposited on thermally oxidized Si substrates with UL materials (Ta, Pt, W, Ta/W), CoFeB (1.0 nm), MgO (1.6 nm), and AlOx (2 nm) layers. Data is collected from anomalous Hall resistance measurements under varying gate voltages.
3：0 nm), MgO (6 nm), and AlOx (2 nm) layers. Data is collected from anomalous Hall resistance measurements under varying gate voltages.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Magnetron sputtering system (DC and RF sputtering), photolithography and ion milling equipment, atomic layer deposition for ZrO2 gate oxide, Hall bar structure with dimensions 75 μm long and 5 μm wide, and a square-shaped FM island of 4x4 μm2.
4：Experimental Procedures and Operational Workflow:
Samples are deposited, annealed at 250-350°C, patterned into Hall bars, and a ZrO2 gate oxide is deposited. Anomalous Hall resistance is measured under a series of gate voltages (+22V, 0V, -22V, 0V) to observe changes in coercivity and magnetic anisotropy.
5：Data Analysis Methods:
Anomalous Hall resistance data is analyzed to extract coercivity (Hc) and magnetic anisotropy field (Hk) using the Stoner-Wohlfarth model. VCMA coefficient is calculated based on changes in anisotropy energy with electric field.
独家科研数据包，助您复现前沿成果，加速创新突破
获取完整内容
