arXiv subjects

B. Dupé

Publications and source records attributed to B. Dupé.

4 recordsLinked to original sources

arXiv2020

Dzyaloshinskii-Moriya interaction induced by an ultrashort electromagnetic pulse: Application to coherent (anti)ferromagnetic skyrmion nucleation

We show how a Dzyaloshinskii-Moriya interaction can be generated in an ultrathin metal film from the induced internal electric field created by an ultrashort electromagnetic pulse. This interaction does not require structural inversion-symmetry breaking, and its amplitude can be tuned depending on the amplitude of the field. We perform first-principles calculations to estimate the strength of the field-induced magnetoelectric coupling for ferromagnetic Fe, Co, and Ni, and antiferromagnetic Mn, as well as FePt alloys. Last, using atomistic simulations, we demonstrate how an isolated antiferromagnetic skyrmion can be coherently nucleated from the collinear background by an ultrashort pulse in electric field on a 100-fs timescale.

cond-mat.mes-hall↗

arXiv2020

Exchange Splitting of a Hybrid Surface State and Ferromagnetic Order in a 2D Surface Alloy

Surface alloys are highly flexible materials for tailoring the spin-dependent properties of surfaces. Here, we study the spin-dependent band structure of a DyAg$_2$ surface alloy formed on an Ag(111) crystal. We find a significant exchange spin-splitting of the localized Dy 4f states pointing to a ferromagnetic coupling between the localized Dy moments at $40\,$K. The magnetic coupling between these moments is mediated by an indirect, RKKY-like exchange coupling via the spin-polarized electrons of the hole-like Dy-Ag hybrid surface state.

cond-mat.mes-hall↗

arXiv2017

Enhanced skyrmion stability due to exchange frustration

Skyrmions are localized, topologically non-trivial spin structures which have raised high hopes for future spintronic applications. A key issue is skyrmion stability with respect to annihilation into the ferromagnetic state. Energy barriers for this collapse have been calculated taking only nearest neighbor exchange interactions into account. Here, we demonstrate that exchange interactions beyond nearest neighbors can be essential to describe stability of skyrmionic spin structures. We focus on the prototypical film system Pd/Fe/Ir(111) and demonstrate that an effective nearest-neighbor exchange or micromagnetic model can only account for equilibrium properties such as the skyrmion profile or the zero temperature phase diagram. However, energy barriers and critical fields of skyrmion collapse as well as skyrmion lifetimes are drastically underestimated since the energy of the transition state cannot be accurately described. Antiskyrmions are not even metastable. Our work shows that frustration of exchange interactions is a route towards enhanced skyrmion stability even in systems with a ferromagnetic ground state.

cond-mat.mtrl-sci↗

arXiv2015

Engineering skyrmions in transition-metal multilayers for spintronics

Magnetic skyrmions are localized, topologically protected spin-structures that have been proposed for storing or processing information due to their intriguing dynamical and transport properties. Important in terms of applications is the recent discovery of interface stabilized skyrmions as evidenced in ultra-thin transition-metal films. However, so far only skyrmions at interfaces with a single atomic layer of a magnetic material were reported, which greatly limits their potential for application in devices. Here, we predict the emergence of skyrmions in [4d/Fe_2/5d]_n multilayers, i.e. structures composed of Fe biatomic layers sandwiched between 4d- and 5d-transition-metal layers. In these composite structures, the exchange and the Dzyaloshinskii-Moriya interactions which control skyrmion formation can be tuned separately by the two interfaces. This allows engineering skyrmions as shown based on density functional theory and spin dynamics simulations.

cond-mat.mtrl-sci↗