Low Relaxation Rate in Epitaxial Vanadium-Doped Ultrathin Iron Films

Abstract

The longest relaxation time and sharpest frequency content in ferromagnetic precession is determined by the intrinsic (Gilbert) relaxation rate G. For many years, pure iron (Fe) has had the lowest known value of G = 57 MHz for all pure ferromagnetic metals or binary alloys. We show that an epitaxial iron alloy with vanadium (V) possesses values of G which are significantly reduced to 35 +/- 5 MHz at 27% V. The result can be understood as the role of spin-orbit coupling in generating relaxation, reduced through the atomic number Z.

Tunnel magnetoresistance effect and magnetic damping in half-metallic Heusler alloys

“…The deviation of the g value from 2, g-2, is roughly proportional to the spin-orbit parameter in the 3d-band, and is also related to the orbital magnetic moment, so that magnetic damping tends to decrease with decreasing orbital magnetic moment or average atomic number of elements included in ferromagnetic metals. Such discussions are given, together with experimental low damping constants observed in the NiMnSb half-Heusler alloy [10] and Fe-V binary alloys [12]. From observation of equation (3.2), magnetic damping can also vary with DOS.…”

“…Damping for various metals and alloys has been studied experimentally by several groups. It has been reported by these groups that very low damping constants can be exhibited in some Co-based Heusler alloys, half-Heusler alloys and iron-vanadium alloys [10][11][12][13]. In particular, Heusler alloys are very attractive materials because some have both small damping constants and very large spin polarization [14].…”

Quadratic Scaling of Intrinsic Gilbert Damping with Spin-Orbital Coupling inL10FePdPt Films: Experiments andAb InitioCalculations

“…In the SOC torque-correlation model proposed by Kamberský, contributions of intraband and interband transitions are thought to play a dominant role in the α 0 at low and high temperatures T and are predicted to be proportional to ξ 3 (ξ=the SOC strength) and ξ 2 , respectively 10,14 . Up to date, however, no experiments have been reported to demonstrate the quantitative relationship between α 0 and ξ although many experimental attempts have been made to study the α 0 in various metallic and alloy films [16][17][18][19][20][21][22][23] . It is hard to rule out effects other than the SOC because α 0 is also strongly related to parameters such as the electron scattering time and density of state D(E F ) at Fermi surface E F 21,23,24 which in turn change among various metals and alloys.…”

Local control of magnetic damping in ferromagnetic/non-magnetic bilayers by interfacial intermixing induced by focused ion-beam irradiation

“…11 However, in the case of Cr, the damping varies according to whether the Cr is co-sputtered or ion-implanted, 10 with the biggest increase observed for implantation. With the exception of recent work on epitaxial vanadium-doped iron, 17 the addition of dopants typically increases damping. 8 Spin-wave waveguides have recently been fabricated by implanting Cr ions in selective areas of NiFe by lithographic patterning.…”