Temperature dependence of intrinsic and extrinsic contributions to anisotropic magnetoresistance

Electrical conduction in magnetic materials depends on their magnetization configuration, resulting in various magnetoresistances (MRs). The microscopic mechanisms of MR have so far been attributed to either an intrinsic or extrinsic origin, yet the contribution and temperature dependence of either origin has remained elusive due to experimental limitations. In this study, we independently probed the intrinsic and extrinsic contributions to the anisotropic MR (AMR) of a permalloy film at varying temperatures using temperature-variable terahertz time-domain spectroscopy. The AMR induced by the scattering-independent intrinsic origin was observed to be approximately 1.5% at T = 16 K and is virtually independent of temperature. In contrast, the AMR induced by the scattering-dependent extrinsic contribution was approximately 3% at T = 16 K but decreased to 1.5% at T = 155 K, which is the maximum temperature at which the AMR can be resolved using THz measurements. Our results experimentally quantify the temperature-dependent intrinsic and extrinsic contributions to AMR, which can stimulate further theoretical research to aid the fundamental understanding of AMR.

Поверхностные магнитостатические волны в пленках железо-иттриевого граната с поверхностной субволновой метаструктурой из пленки пермаллоя

The frequency dependencies of the transmission coefficient of surface magnetostatic waves (SMSW) propagating in subwavelength magnonic structures obtained by depositing of 1D and 2D thin-film metastructures based on a permalloy film 40 nm thick onto the surface of yttrium iron garnet (YIG) film were experimentally studied. Such structures in the frequency range 1–10 GHz (typical for the study of SMSW in YIG films) lead to modulation of attenuation and the effective internal magnetic field in the YIG film. The possibility of controlling the parameters of the bandwidth of the SMSW by the choice of the direction of magnetization in the plane of the structures relative to their axis of symmetry is shown.

Effects of average grain size on the magnetic properties of permalloy films

In this paper the results of substrate temperature effects on average grain size in FeNi 20:80 are shown. It was found that with an increase of the substrate temperature from 270 to 390 °C, the anisotropic magnetoresistive (AMR) effect increases from 1.2 to 2.3% and the coercive force from 1.6 to 5.3 Oe. The presence of two conflicting processes: the task of increasing AMR effect to achieve high sensitivity of AMR-sensor and to decrease the coercive force to increase the precision of conversion, leads to the necessity to find the optimum deposition temperature of the permalloy film. The dependence of the AMR effect and the coercive force on the substrate temperature during deposition was obtained. This dependence shows that the substrate temperature increasing above 320 °C leads to coercive force increasing and does not lead to a substantial AMR increasing. In this regard, the substrate temperature 320 °C was determined as optimal.