title: Nanoscale layer-selective readout of magnetization direction from a magnetic multilayer using a spin-torque oscillator.
abstract: Technology for detecting the magnetization direction of nanoscale magnetic material is crucial for realizing high-density magnetic recording devices. Conventionally, a magnetoresistive device is used that changes its resistivity in accordance with the direction of the stray field from an objective magnet. However, when several magnets are near such a device, the superposition of stray fields from all the magnets acts on the sensor, preventing selective recognition of their individual magnetization directions. Here we introduce a novel readout method for detecting the magnetization direction of a nanoscale magnet by use of a spin-torque oscillator (STO). The principles behind this method are dynamic dipolar coupling between an STO and a nanoscale magnet, and detection of ferromagnetic resonance (FMR) of this coupled system from the STO signal. Because the STO couples with a specific magnet by tuning the STO oscillation frequency to match its FMR frequency, this readout method can selectively determine the magnetization direction of the magnet.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Suto
authors.forename: Tazumi
authors.initials: T
authors.lastname: Nagasawa
authors.forename: Kiwamu
authors.initials: K
authors.lastname: Kudo
authors.forename: Koichi
authors.initials: K
authors.lastname: Mizushima
authors.forename: Rie
authors.initials: R
authors.lastname: Sato