AMR vs. GMR Vs. TMR magnetic sensors

Many companies are working hard in the design, development and fabrication of Anisotropic Magneto-Resistance (AMR), Giant Magneto-Resistance (GMR), and Magnetic Tunneling Junction (MTJ) magnetic thin film sensors.

Working with a variety of magnetic materials (see table below) AMS deposition techniques achieve optimal conditions (uniformity, composition control, easy/hard axis orientation). The thickness range of these materials spans from <10Å (1nm) for GMR and MTJ applications to >10µ for magnetic shields and flux-concentrators.

Materials Magnetic Properties Application Deposition Technique Typical Layer Thk.
NiFe (Permalloy) Soft AMR, GMR sensors Sputtered 10Ǻ – 1000Ǻ
NiFe (Permalloy) Soft Shields, Poles Plated 1µm – 10µm
NiFe (45/55) Soft, higher moment Shields, Poles Plated 1µm-10µm
CoPt Hard, high coercivity Permanent magnets Sputtered 500 Ǻ – 10 µm
Co ternary alloy Soft, higher moment Shields, Inductors, Poles Sputtered 1 µm – 10 µm
IrMn, PtMn Anti-ferromagnetic GMR, MTJ sensors Sputtered 50 – 250 Ǻ

We use several different vacuum deposition tools to deposit a variety of magnetic materials, including the GMR / MTJ cluster disposition system seen below. The metrology equipment for the characterization of magnetic materials includes BH loopers, VSM (Vibrating Sample Magnetometer), MFM (Magnetic Force Microscopy) and RMM (Remanent Moment Magnetization).


Typical AMR sensors transfer curve
Typical AMR transfer curve