In spin valve sensors, the bias point caused by the interlayer coupling between the pinned layer and the free layer is a crucial issue encountered in the design process, which degrades the responsivity and the weak-field detection feature. In tackling this issue, we present the magnetic bias technique for efficient control of the bias point of the pinned spin valve (PSV). Specifically, the magnetic field that creates a shift of the bias point is generated by a coil being wrapped around the PSV devices. The PSV multilayer structure, Ta(5 nm)/NiFe(3 nm)/CoFe(4.5 nm)/Cu(1.5 nm)/CoFe(2.4 nm)/IrMn(10 nm)/Ta(5 nm), was fabricated using DC magnetron sputtering deposition. The PSV devices patterned by using a simple lift-off technique have a dimension of 1.5 µm × 200 µm. The bias magnetic field was tuned between ± 5 mT by changing an external DC current. Our experimental results indicate that the bias point can be efficiently controlled via a simple adjustment of the current in the bias coil. Consequently, the device responsivity was remarkably enhanced by a factor of 6.75, from 0.8 V/T to 5.4 V/T, leading to a decrease of the detectivity (field noise) from 366 nT/√Hz@1 Hz to 108 nT/√Hz@1 Hz. Additionally, the field noise was further suppressed by a factor of 5 from 363 nT/√Hz@1 Hz to 72 nT/√Hz@1 Hz by applying the AC-driven mode in the half-bridge PSV. The simplicity of our proposed technique makes it particularly pertinent to PSV sensor designs for low-field applications.

在自旋阀传感器中，由钉扎层和自由层之间的层间耦合引起的偏置点是设计过程中遇到的关键问题，这会降低响应度和弱场检测功能。为了解决这个问题，我们提出了一种磁性偏置技术，用于有效控制固定旋转阀（PSV）的偏置点。具体地，通过在PSV装置周围缠绕线圈来产生产生偏置点偏移的磁场。使用以下材料制作了PSV多层结构：Ta（5 nm）/ NiFe（3 nm）/ CoFe（4.5 nm）/ Cu（1.5 nm）/ CoFe（2.4 nm）/ IrMn（10 nm）/ Ta（5 nm）。直流磁控溅射沉积。通过使用简单的剥离技术图案化的PSV装置具有1.5的尺寸 μ米×200  μ米 通过改变外部直流电流，可将偏置磁场调整在±5 mT之间。我们的实验结果表明，可以通过简单调整偏置线圈中的电流来有效地控制偏置点。因此，设备的响应度从0.8 V / T显着提高了6.75倍，至5.4 V / T，导致检测率（场噪声）从366 nT /√Hz@ 1 Hz降低至108 nT /√ Hz @ 1 Hz。此外，通过在半桥PSV中采用交流驱动模式，场噪声进一步得到了从363 nT /√Hz@ 1 Hz到72 nT /√Hz@ 1 Hz的5倍抑制。我们提出的技术的简单性使其特别适用于低场应用的PSV传感器设计。