ترغب بنشر مسار تعليمي؟ اضغط هنا

Spin-Polarized Standing Waves in the Fermi Surface of a Ferromagnetic Thin Film

54   0   0.0 ( 0 )
 نشر من قبل Joerg Schaefer
 تاريخ النشر 2005
  مجال البحث فيزياء
والبحث باللغة English
 تأليف J. Schaefer




اسأل ChatGPT حول البحث

The spin-selective electron reflection at a ferromagnetic-paramagnetic interface is investigated using Fe films on a W(110) substrate. Angle-resolved photoemission of the majority and minority Fermi surfaces of the Fe film is used to probe standing wave formation. Intense quantum well states resulting from interfacial reflection are observed exclusively for majority states. Such high spin polarization is explained by the Fermi surface topology of the connecting substrate, and we argue that Fe/W is a particularly suitable interface for that purpose.



قيم البحث

اقرأ أيضاً

We calculate expressions for the state-dependent quasiparticle lifetime, the thermal conductivity $kappa$, the shear viscosity $eta$, and discuss the spin diffusion coefficient $D$ for Fermi-liquid films in two dimensions. The expressions are valid f or low temperatures and arbitrary polarization. The low-temperature expressions for the transport coefficients are essentially exact. We find that $kappa^{-1} sim T ln{T}$, and $eta^{-1} sim T^{2}$ for arbitrary polarizations $0 le {mathcal{P}} le 1$. We note that the shear viscosity requires a unique analysis. We utilize previously determined values for the density and polarization dependent Landau parameters to calculate the transition probabilities in the lowest order $ell = 0$ approximation, and thus we obtain predictions for the density, temperature and polarization dependence of the thermal conductivity, shear viscosity, and spin diffusion coefficient for thin he3 films. Results are shown for second layer he3 films on graphite, and thin he3-he4 superfluid mixtures. The density dependence is discussed in detail. For $kappa$ and $eta$ we find roughly an order of magnitude increase in magnitude from zero to full polarization. For $D$ a simialr large increase is predicted from zero polarization to the polarization where $D$ is a maximum ($sim 0.74$). We discuss the applicability of he3 thin films to the question of the existence of a universal lower bound for the ratio of the shear viscosity to the entropy density.
The Fermi surface of a conventional two-dimensional electron gas is equivalent to a circle, up to smooth deformations that preserve the orientation of the equi-energy contour. Here we show that a Weyl semimetal confined to a thin film with an in-plan e magnetization and broken spatial inversion symmetry can have a topologically distinct Fermi surface that is twisted into a $mbox{figure-8}$ $-$ opposite orientations are coupled at a crossing which is protected up to an exponentially small gap. The twisted spectral response to a perpendicular magnetic field $B$ is distinct from that of a deformed Fermi circle, because the two lobes of a mbox{figure-8} cyclotron orbit give opposite contributions to the Aharonov-Bohm phase. The magnetic edge channels come in two counterpropagating types, a wide channel of width $beta l_m^2propto 1/B$ and a narrow channel of width $l_mpropto 1/sqrt B$ (with $l_m=sqrt{hbar/eB}$ the magnetic length and $beta$ the momentum separation of the Weyl points). Only one of the two is transmitted into a metallic contact, providing unique magnetotransport signatures.
The antiferromagnetic molecular finite chain Cr6 was studied by inelastic neutron scattering. The observed magnetic excitations at 2.6 and 4.3 meV correspond, due to the open boundaries of a finite chain, to standing spin waves. The determined energy spectrum revealed an essentially classical spin structure. Hence, various spin-wave theories were investigated in order to assess their potential for describing the elementary excitations of finite spin systems.
The Talbot effect has been known in optics since XIX century and found various technological applications. In this paper, we demonstrate with the help of micromagnetic simulations this self-imaging phenomenon for spin waves propagating in a thin ferr omagnetic film magnetized out-of-plane. We show that the main features of the obtained Talbot carpets for spin waves can be described, to a large extent, by the approximate analytical formulas yielded by the general analysis of the wave phenomena. Our results indicate a route to a feasible experimental realisation of the Talbot effect at low and high frequencies and offer interesting effects and possible applications in magnonics.
135 - A. Yamaguchi , K. Motoi , 2008
The rectifying effect of radio-frequency (RF) current is highly sensitive in terms of the spatial spin distribution and dynamics. It emerged that an additional spin wave mode was stimulated by the direct-current (DC) current and that this spin wave w as detectable via rectification of the RF current. A phenomenological model to describe the time-dependent anisotropic magnetoresistance or time-dependent planer Hall effect is proposed and found to correlate well to the experimental results. The nonlinear spin dynamics accompanying additional spin waves are studied as functions of the RF and DC currents, the external magnetic field, and the applied field direction.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا