There is provided in accordance with the present invention a magnetic encoder including a ring-shaped multipolar magnet having a plurality of opposite magnetic poles alternating with each other in a direction circumferentially thereof, and a core metal for supporting the multipolar magnet. For example, in some implementations, the method includes selecting a first set of one or more soft information values and receiving a read data command. A second etching process is performed on the barrier metal layer to expose upper corners of the trench while leaving the trench substantially covered with the barrier metal layer.