Planar Hall resistance ring sensor based on NiFe/Cu/IrMn trilayer structure

Abstract

International audienceWe have investigated the sensitivity of a planar Hall resistance sensor as a function of the ring radius in the trilayer structure Ta(3)/IrMn(10)/Cu(0.2)/NiFe(10)/Ta(3) (nm). The diagonal components of magnetoresistivity tensor in rectangular prism corresponding to anisotropic magnetoresistance are few ten times larger than that of off-diagonal component corresponding to planar Hall resistance. However, it is noteworthy that the resultant contribution is governed by the off-diagonal components due to the cancellation of diagonal components in the self-balanced bridge configuration. Both the experimental and theoretical results show that the sensitivity varies linearly with the ring radius. In multi-ring architecture, the circumference can be increased to a limit, which consequently enhances sensitivity. We found the sensitivity of the investigated 7-rings planar Hall to be more than 600 uV/Oe

Planar Hall effect bridge sensors with NiFe/Cu/IrMn stack optimized for self-field magnetic bead detection

“…A similar trilayer stack was later used in multi-ring planar Hall effect bridge sensors. 25 The maximum signal that can be obtained from a sensor constructed from a given stack depends not only on the low-field sensitivity of the sensor but also on the maximum applicable sensor bias current. Thus, it is not a priori clear whether the optimum magnetic stack for magnetic field detection is also the best stack for detection of magnetic beads using the sensor self-field.…”

Comment on “Planar Hall resistance ring sensor based on NiFe/Cu/IrMn trilayer structure” [J. Appl. Phys. 113, 063903 (2013)]

“…(2) of p= ffiffi ffi 2 p instead of the claimed ffiffi ffi 2 p . However, we do not agree on the signal calculation for a ring sensor derived by Sinha et al 1 We are able to follow the derivation of the sensor signal until their Eq. (4), which for a general Wheatstone bridge should read…”

Experimental comparison of ring and diamond shaped planar Hall effect bridge magnetic field sensors

“…Some sensors also included a thin copper layer between the FM and AFM layers to weaken the exchange bias coupling. 7 Upon application of a magnetic field B y along the y-direction, the equivalent single domain magnetization angle h 6 for a sensor branch can be obtained by minimizing the energy density, u. The energy density normalized with the saturation magnetization M s of the ferromagnetic layer is…”

“…16 Also, the use of PHEB sensors for both volume-and surface-based biodetection schemes using only the field from the sensor bias current as magnetic field excitation has been demonstrated. [17][18][19] While these PHEB sensors showed improved signal-tonoise ratio, both ring shaped sensors with curved resistors ("ring sensors") 7,15 and diamond shaped sensors with straight resistors ("diamond sensors") 14,20 have been argued to be the superior design. The pros and cons of ring and diamond sensors were recently discussed theoretically for the detection of external magnetic fields and a theoretical analysis predicted the diamond sensors to be 41% more sensitive than the corresponding ring sensors for the same bias current.…”

“…Magnetic field sensors based on giant magneto-resistance, 1,2 magnetic tunneling resistance, 3,4 and anisotropic magnetoresistance [5][6][7][8] effects have been presented in the literature with special focus on their application for magnetic biosensing. 9 For such applications, magnetic beads are used as readout labels and are linked to the surface of the sensor chip in the presence of the target analyte.…”