Temperature and angular dependence of the anisotropic magnetoresistance in epitaxial Fe films

Abstract

We perform detailed temperature dependent measurements of the magnetoresistance ͑MR͒ and its angular dependence of epitaxial Fe ͑110͒ films. The angular dependence of the MR at Hϭ10 kOe is found to change strongly when going from Tϭ4.2 K to Tϭ230 K. We analyze the data on the basis of Döring's equation. Second-and fourth-order angular dependent terms are found to be of equal importance, indicating strong deviations of the MR from a simple cos 2 dependence. One of the MR components is the ordinary or Lorentz magnetoresistance, which is strong at low temperatures and becomes smaller at higher temperatures, due to the reduction of the mean free path. By subtracting the ordinary magnetoresistance from the MR data we obtain the anisotropic magnetoresistance. We decompose the temperature dependent anisotropic magnetoresistance in the temperature dependent k constants of Döring's equation. These constants show a reduction between Tϭ20 K and Tϭ100 K, which reflects the observed decrease of the anisotropic magnetoresistance. We present arguments that the temperature dependence of the anisotropic magnetoresistance is most likely due to the change from defect-dominated scattering to phonon-dominated scattering, each of which has its own anisotropic magnetoresistance.

Origin of the Planar Hall Effect in NanocrystallineCo60Fe20B20

“…3(a) and 3(b), respectively. The angular dependence of the AMR ratios is rather strong, as expected for single crystals [24,25]. The main effect of adding boron is a reduction of the AMR ratios while qualitatively the angular dependence of the AMR ratios is similar in the CoFe and CoFeB systems.…”

Anomalous anisotropic magnetoresistance in epitaxialFe3O4thin films on MgO(001)

“…However in single crystals and epitaxial films, it contains higher order terms which reflect the symmetry of the crystals. 39,40 Using the phenomenological description for the anisotropic magnetoresistance, the dependence of the resistivity tensor with respect to the angle between magnetization and current can be calculated. Expanding the resistivity tensor as a function of the direction cosines of the magnetization and considering the symmetric part only gives:…”

Anisotropic Magnetoresistance Components in (Ga,Mn)As

“…Despite its importance in magnetic recording technologies the understanding of the microscopic physics of this spin-orbit (SO) coupling induced effect is relatively poor. Phenomenologically, AMR has a non-crystalline component, arising from the lower symmetry for a specific current direction, and crystalline components arising from the crystal symmetries [1,2]. In ferromagnetic metals, values for these coefficients can be obtained by numerical ab initio transport calculations [3], but these have no clear connection to the standard physical model of transport arising from spin dependent scattering of current carrying low mass s-states into heavymass d-states [4].…”

“…In ferromagnetic metals, values for these coefficients can be obtained by numerical ab initio transport calculations [3], but these have no clear connection to the standard physical model of transport arising from spin dependent scattering of current carrying low mass s-states into heavymass d-states [4]. Experimentally, the non-crystalline and, the typically much weaker, crystalline AMR components in metals have been indirectly extracted from fitting the total AMR angular dependences [2].…”

“…In ferromagnetic metals, values for these coefficients can be obtained by numerical ab initio transport calculations [3], but these have no clear connection to the standard physical model of transport arising from spin dependent scattering of current carrying low mass s-states into heavymass d-states [4]. Experimentally, the non-crystalline and, the typically much weaker, crystalline AMR components in metals have been indirectly extracted from fitting the total AMR angular dependences [2].Among the remarkable AMR features of (Ga,Mn)As ferromagnetic semiconductors are the opposite sign of the non-crystalline component (compared to most metal ferromagnets) and the crystalline terms reflecting the rich magnetocrystalline anisotropies [5,6,7,8,9,10,11]. Microscopic numerical simulations [6,12] consistently describe the sign and magnitudes of the non-crystalline AMR and capture the more subtle crystalline terms associated with e.g.…”