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Research Projects


 

 

Project  Title  Partner  Objective
 ESR1 Spin currents excitation and detection in structures grown by shadow mask angular deposition LEEDS

Transform charge current into spin current with high efficiency through e.g. high spin accumulation at the interface using high polarisation electrodes – developed for the purpose of optimisation of spin currents for devices. Acoutsically excite SSE in appropriately chosen materials with high magnon-phonon coupling constants.

 ESR2 Coherent Phonon Excitation of SSE LEEDS

Characterise and understand coherent phonon control of Spin Seebeck Effect. Test the current theories of this effect as a function of temperature.

 ESR3 Spin transfer torque nanodevices

INL

To obtain efficient spin transfer torque effect on nanopillars based on magnetic tunnel junctions (MgO barriers) with critical switching currents below 105 A/cm2 . Nano-oscillators will be measured and the RF signal generated by an array of nano-oscillators will be used as feed-back in the synchronization of the nano-oscillators.

 ESR4 Magnetoresistive Material optimization for logic nanodevices INESC-MN

To obtain state-of-the-art magnetic tunnel junction materials based on MgO barriers, suitable for logic nanodevices. The key properties are:

  • Large tunnel magnetoresistance ratio (TMR > 200%) and low resistance-area products (RxA < 10 Ohm.um2)
  • Control of the free layer switching characteristics (low Hf < 5 Oe, low coercivity Hc< 2Oe)
  • Reference layer stability down to 50nm dimensions (upon annealing at 360ºC)
 ESR5 Nanopatterning of lateral spin devices IBM

Detection and characterisation of spin torque effects in metallic ferromagnets. Investigation of domain walls in nanowires with constrained geometries.

 ESR6 Magnetic tunnel barriers for spin filters UCAM

Increasing the injection polarisation of charge currents by using spin filters and materials with large spin-splitting or high intrinsic polarisation.

 ESR7 Thermal spin pumping through a Schottky barrier into GaAs HCL

Investigation of a thermal spin current from a ferromagnet to GaAs by Seebeck spin tunnelling

  • investigate various magnon excitation mechanisms in ferromagnetic injection electrode
    • thermal Joule heating (direct current heating of the metal or by sending current
    • pulses through an stripe line
    • thermal heating by laser pulse excitation
    • FMR excitation of magnons
  • develop an efficient detection method, based on
    • inverse spin Hall detection in GaAs device using Hall device symmetry and Hanle spin precession
    • non-local spin-valve detection in GaAs device with ferromagnetic detection electrodes
  • investigation of combined thermal and electrical spin injection into GaAs
 ESR8 Spin Seebeck effects in tunnelling

INESC-MN

To observe a STT mechanism driven by a thermal gradient (using the Spin Seebeck effect), through magnetization switching of state-of-the-art Spintronic nanodevices.

 ESR9 Investigation of the origin of the spin dependent Seebeck effect in (Ga,Mn)As and Py thin films

UREG 

Detect spin Seebeck effect in metallic (Permalloy) films grown on various substrates (GaAs, MgO, Sapphire etc.) as well as in GaMnAs/GaAs diluted magnetic semiconductor systems. Investigation of various spurious effects (e.g. planar Nernst effect, anomalous Nernst effect).

 ESR10

Theory of spintronic devices

NTNU

Understand the magnitude and relevance of spin-swapping versus spin Hall effects in 4-terminal devices. Predict how spin-orbit interaction influence spin-pumping and spin-transfer torques.  

 ESR11

Dynamic measurements of the spin Hall angle

UREG

Sample design for Spin Hall angle measurement using spin pumping via ferromagnetic resonance and detection via the inverse spin Hall effect (ISHE). Elimination of spurious effects arising from sample design (capacitive and inductive coupling) as well as anisotropic magnetoresistance. Determination of conductivity and Spin Hall conductivity.

 ER1

Magnetic characterisation of spin current nanowires

IBM

Develop highly sensitive magnetic characterisation techniques. Apply these techniques for the investigation of magnetic nanowires and novel lateral spin devices.

 ER2

Magnetic tunnel junctions for logic nanodevices

INL

Integrate optimized materials and nanofabrication of functional devices with reproducible and controlled frequency spectra.

 ER3

Theory of spintronic devices

TUD

Theory of spin, charge and heat transport in ferromagnetic/normal metal heterostructures

  • Metallic vs. insulating ferromagnets
  • Elucidating the effects of spin Hall and anomalous Hall effects 
  • AC spin pumping induced inverse spin Hall effect 
  • Support of experimental activities in Spinicur
ER4

 Magnetic Seebeck effect in tunnel junctions with only one magnectically ordered eletrode

 HCL

Recently, the magnetic Seebeck effect has been discovered in conventional magnetic tunnel junctions with two ferromagnetic electrodes separated by a tunneling barrier. [M. Walter - Nature Materials 10, 742–746 (2011)] In such TMR type of devices, both electrically and thermally driven electron transport depend on the relative magnetisation orientation between the two ferromagnetic electrodes.

Electrically driven transport studies in tunnelling devices with only one magnetically ordered electrode has recently lead to the first realization of the antiferromagnetic tunneling anisotropic magnetoresistance [Park, et al - Nature Materials 10, 5, 347]. Here, electron transport is affected by the magnetization orientation dependency of density of state and chemical potential.

In this ER4 project, we investigate the dependency of thermally driven tunnel current through tunneling devices with only a single magnetically ordered electrode and a non-magnetic counter electrode. We plan to study tunneling devices with both a single ferromagnetic or an antiferromagnetic electrode. The moment orientations in antiferromagnetic tunneling devices are controlled by an externally applied magnetic field via the exchange spring effect to a ferromagnet. [A. Scholl, et al., Phys. Rev. Lett. 92, 247201 (2004)].

We will employ laser and/or current Joule induced generated heating to generate a thermal gradient across the tunneling barrier. Several tunneling barriers including crystalline MgO to amorphous AlOx and Several antiferromagnets material such as IrMn will be investigated.