Impact of electromagnetic fields and heat on spin transport signals in Y$_{3}$Fe$_{5}$O$_{12}$

2019

Exploring new strategies to perform magnon logic is a key requirement for the further development of magnon-based spintronics. In this work, we realize a three-terminal magnon transport device to study the possibility of manipulating magnonic spin information transfer in a magnetic insulator via localized magnetic fields and heat generation. The device comprises two parallel Pt wires as well as a Cu center wire that are deposited on the ferrimagnetic insulator Y$_{3}$Fe$_{5}$O$_{12}$. While the Pt wires act as spin current injector and detector, the Cu wire is used to create local magnetostatic fields and additional heat, which impact both the magnetic configuration and the magnons within t…

The challenge in realizing an exchange coupled BiFeO3-double perovskite bilayer

2020

Abstract In this work we propose a device design for efficient voltage control of magnetism. The magnetization of a ferrimagnetic double perovskite may be manipulated by an exchange coupled layer of multiferroic BiFeO3. Bilayers of Barium doped BiFeO3 and ferrimagnetic double perovskite Sr2FeMoO6 have been prepared by pulsed laser deposition motivated by the possibility of strong interlayer exchange coupling. While single layers of each material show high quality we observe that in both stacking orders the first layer decomposes during the deposition of the second layer. The reason for the decomposition are strongly differing growth conditions for BiFeO3 and Sr2FeMoO6. This means that the g…

Impact of electromagnetic fields and heat on spin transport signals in Y3Fe5O12

2019

Exploring new strategies to perform magnon logic is a key requirement for the further development of magnon-based spintronics. In this paper, we realize a three-terminal magnon transport device to study the possibility of manipulating magnonic spin information transfer in a magnetic insulator via localized magnetic fields and heat generation. The device comprises two parallel Pt wires as well as a Cu center wire that are deposited on the ferrimagnetic insulator ${\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$. While the Pt wires act as spin current injector and detector, the Cu wire is used to create local magnetostatic fields and additional heat, which impact both the magnetic configur…

Terahertz Spin‐to‐Charge Conversion by Interfacial Skew Scattering in Metallic Bilayers

2021

The efficient conversion of spin to charge transport and vice versa is of major relevance for the detection and generation of spin currents in spin‐based electronics. Interfaces of heterostructures are known to have a marked impact on this process. Here, terahertz (THz) emission spectroscopy is used to study ultrafast spin‐to‐charge‐current conversion (S2C) in about 50 prototypical F|N bilayers consisting of a ferromagnetic layer F (e.g., Ni81Fe19, Co, or Fe) and a nonmagnetic layer N with strong (Pt) or weak (Cu and Al) spin‐orbit coupling. Varying the structure of the F/N interface leads to a drastic change in the amplitude and even inversion of the polarity of the THz charge current. Rem…

Magnetoelectric properties of epitaxialFe3O4thin films on (011) PMN-PT piezosubstrates

2015

We determine the magnetic and magnetotransport properties of 33 nm thick ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ films epitaxially deposited by rf-magnetron sputtering on unpoled (011) ${[{\mathrm{PbMg}}_{1/3}{\mathrm{Nb}}_{2/3}{\mathrm{O}}_{3}]}_{0.68}\ensuremath{-}{[{\mathrm{PbTiO}}_{3}]}_{0.32}$ (PMN-PT) substrates. The magnetoresistance (MR), as well as the magnetization reversal, strongly depend on the in-plane crystallographic direction of the epitaxial (011) ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ film and strain. When the magnetic field is applied along [100], the magnetization loops are slanted and the sign of the longitudinal MR changes from positive to negative around the Verwey transiti…

Skyrmion pinning energetics in thin film systems

2022

AbstractA key issue for skyrmion dynamics and devices are pinning effects present in real systems. While posing a challenge for the realization of conventional skyrmionics devices, exploiting pinning effects can enable non-conventional computing approaches if the details of the pinning in real samples are quantified and understood. We demonstrate that using thermal skyrmion dynamics, we can characterize the pinning of a sample and we ascertain the spatially resolved energy landscape. To understand the mechanism of the pinning, we probe the strong skyrmion size and shape dependence of the pinning. Magnetic microscopy imaging demonstrates that in contrast to findings in previous investigation…

Control of the Magnetic Configuration of Ferromagnetic Nanostructures Across the Structural Phase Transition of Vanadium Dioxide

2016

We investigate the effect of the structural phase transition in VO 2 in magnetoelastically coupled heterostructures of VO 2 and Ni. Continuous and nano-patterned Ni layers were used, and we found reversible and reproducible magnetic domain switching induced by the VO 2 structural phase transition. The magnetic states of the nano-patterned ferromagnetic elements were dominated by topographic features which generated strong pinning but still allowed for a reversible switching between the states. Our measurements constitute a key step for the use of the VO 2 phase transition for ultrafast dynamical studies of the inverse mangetostrictive effect, and eventually employing the effect for ultrafas…

Impact of electromagnetic fields and heat on spin transport signals in Y 3 Fe 5 O 12

The effect of interface roughness on exchange bias in La0.7Sr0.3MnO3 - BiFeO3 heterostructures

2016

We characterized the interfaces of heterostructures with different stack sequences of La0.7Sr0.3MnO3/BiFeO3 (LSMO/BFO) and BFO/LSMO using TEM revealing sharp and rough interfaces, respectively. Magnetometry and magnetoresistance measurements do not show a detectable exchange bias coupling for the multistack with sharp interface. Instead, the heterostructures with rough and chemically intermixed interfaces exhibit a sizable exchange bias coupling. Furthermore, we find a temperature-dependent irreversible magnetization behavior and an exponential decay of coercive and exchange bias field with temperature suggesting a possible spin-glass-like state at the interface of both stacks.

Enhancement of spin Hall conductivity in W-Ta alloy

2020

Generating pure spin currents via the spin Hall effect in heavy metals has been an active topic of research in the last decade. In order to reduce the energy required to efficiently switch neighbouring ferromagnetic layers for applications, one should not only increase the charge- to-spin conversion efficiency but also decrease the longitudinal resistivity of the heavy metal. In this work, we investigate the spin Hall conductivity in W_{1-x}Ta_{x} / CoFeB / MgO (x = 0 - 0.2) using spin torque ferromagnetic resonance measurements. Alloying W with Ta leads to a factor of two change in both the damping-like effective spin Hall angle (from - 0.15 to - 0.3) and longitudinal resistivity (60 - 120…

Magnetic configurations in nanostructured Co2MnGa thin film elements

2015

The magnetic configuration of nanostructured elements fabricated from thin films of the Heusler compound Co2MnGa was determined by high-resolution x-ray magnetic microscopy, and the magnetic properties of continuous Co2MnGa thin films were determined by magnetometry measurements. A four-fold magnetic anisotropy with an anisotropy constant of kJ m−3 was deduced, and x-ray microscopy measurements have shown that the nanostructured Co2MnGa elements exhibit reproducible magnetic states dominated by shape anisotropy, with a minor contribution from the magneto-crystalline anisotropy, showing that the spin structure can be tailored by judiciously choosing the geometry.

Impact of the interplay of piezoelectric strain and current-induced heating on the field-like spin–orbit torque in perpendicularly magnetized Ta/Co20…

2021

Spin–orbit torques (SOTs) are known to be the most efficient way to manipulate the magnetization direction by electrical currents. While, conventionally, one symmetry component of the SOTs, namely, the damping-like torque, was considered to play a primary role, recently, the significance of the other component, the field-like torque, has been revised, owing to the non-trivial dynamics it can induce in heavy metal/ferromagnet multilayers. In this work, we first discuss the unusual behavior of the field-like SOT in a Ta/CoFeB/Ta/MgO multilayer system with a reduced magnetic anisotropy and demonstrate an energy-efficient approach to manipulate the magnitude of the SOT effective fields. Finally…

Magnetization reversal of the domain structure in the anti-perovskite nitride Co3FeN investigated by high-resolution X-ray microscopy

2016

We performed X-ray magnetic circular dichroism (XMCD) photoemission electron microscopy imaging to reveal the magnetic domain structure of anti-perovskite nitride Co3FeN exhibiting a negative spin polarization. In square and disc patterns, we systematically and quantitatively determined the statistics of the stable states as a function of geometry. By direct imaging during the application of a magnetic field, we revealed the magnetic reversal process in a spatially resolved manner. We compared the hysteresis on the continuous area and the square patterns from the magnetic field-dependent XMCD ratio, which can be explained as resulting from the effect of the shape anisotropy, present in nano…