Spin Torque Gate Magnetic Field Sensor

Abstract

Spin-orbit torque provides an efficient pathway to manipulate the magnetic state and magnetization dynamics of magnetic materials, which is crucial for energy-efficient operation of a variety of spintronic devices such as magnetic memory, logic, oscillator, and neuromorphic computing. Here, we describe and experimentally demonstrate a strategy for the realization of a spin torque gate magnetic field sensor with extremely simple structure by exploiting the longitudinal field dependence of the spin torque driven magnetization switching. Unlike most magnetoresistance sensors which require a delicate magnetic bias to achieve a linear response to the external field, the spin torque gate sensor can achieve the same without any magnetic bias, which greatly simplifies the sensor structure. Furthermore, by driving the sensor using an ac current, the dc offset is automatically suppressed, which eliminates the need for a bridge or compensation circuit. We verify the concept using the newly developed WTe2/Ti/CoFeB trilayer and demonstrate that the sensor can work linearly in the range of ±3-10 Oe with negligible dc offset.

Wide Linearity Range 3D Magnetic Sensor and Angular Position Detector Based on a Single FePt Spin–Orbit Torque Device

“…Based on the SOT-dominated magnetization reversal, the linear response of anomalous Hall resistance within a wide linear range (±200 Oe) for the x , y , and z components of magnetic fields has been obtained, respectively. More importantly, compared to the previous studies by Li et al (1450 nV Hz –1/2 ) and Guo et al (411 nV Hz –1/2 ), our sensor exhibits a relatively lower magnetic noise level of 7.9 nV Hz –1/2 , improving measurement resolution at the low frequency. The high perpendicular magnetic anisotropy (PMA) of L 1 0 -FePt is able to reduce the sensitivity to temperature variations and external magnetic fields, ensuring reliable long-term performance.…”

“…(1450 nV Hz −1/2 ) 18 and Guo et al (411 nV Hz −1/2 ), 20 our sensor exhibits a relatively lower magnetic noise level of 7.9 nV Hz −1/2 , improving measurement resolution at the low frequency. The high perpendicular magnetic anisotropy (PMA) of L1 0 -FePt is able to reduce the sensitivity to temperature variations and external magnetic fields, ensuring reliable long-term performance.…”

“…Recently, intriguing physical phenomena such as spin–orbit torque (SOT) and the anomalous Hall effect (AHE) are promising to motivate the development of a planar 3D magnetic sensor beyond traditional Hall and MR devices . Based on the SOT effect, Wu et al proposed the spin torque gate (STG) magnetic field sensor, which can achieve a linear response to magnetic field without any magnetic bias, in a simple Hall bar structure . Additionally, You et al have put forward an ingenious approach to distinguishing the three magnetic field components ( H x , H y , and H z ) with alternating driving current directions in a single Hall-bar device. , Moreover, Liu et al demonstrated the ultrahigh sensitivity and low current density in the SOT device with easy-cone magnetic state by exquisite engineering of the magnetic anisotropy in the Pt/Co/Ta heterostructure .…”

Applied Trends in Magnetic Rare Earth/Transition Metal Alloys and Multilayers

“…Since the magnetization switching driven by spin torque depends on the longitudinal magnetic field, Xie et al [ 80 ] have proposed very recently a magnetic field sensor based on a SOT device. It has major advantages over traditional MR sensors, which require a magnetic bias to achieve a linear response to the external field, while the SOT sensor can achieve the same without any magnetic bias.…”

Angular Position Sensor Based on Anisotropic Magnetoresistive and Anomalous Nernst Effect

“…These sensors typically have a much simpler design as compared to the conventional AMR, GMR, and TMR sensors. In fact, all of these sensors, including the SMR sensor [14], spin torque gate (STG) sensor [15], SOT-enabled anomalous Hall (AHE) vector magnetometer [16], and SOT-based magnetic angular sensor [17] are based merely on a simple ultrathin ferromagnet (FM)/heavy metal (HM) bilayer without any magnetic bias, which greatly simplifies the sensor design and reduces the manufacturing cost. However, the SOT-based sensors typically have a relatively small dynamic range, which may limit their applications in settings with a large environmental magnetic field.…”