1. X-ray photoemission electron microscopy (XPEEM)
Carlos A. F. Vaz :: Paul Scherrer Institut
X-ray photoemission electron microscopy (XPEEM)
Hercules School, April 2016

2. Advantages of x-rays for magnetic imaging
chemical sensitivity
elemental and magnetic sensitivity
nm spatial resolution/sub-monolayer sensitivity Fe Co
2 m
14 nm FeCo nanoparticles on Si
Moyer et al, PRB 84, (2011)
No magnetic interaction with the sample
Sub-ns time resolution
6 m NiFe dots; Raabe et al, PRL 94, (2005)

3. Fast dynamics: pulsed structure of SLS
2 mA DtFwhm~70ps
90 ns

4. X-ray magnetic imaging: the XMCD effect
Stohr et al., Surf. Rev. Lett. 5 (1998) 1297

5. Origin of XMCD effect Spin moment
Stoehr, Siegmann, Magnetism, Springer 2006

6. X-ray based magnetic imaging techniques
X-ray holography
Photoelectron
X-ray microscopy
Eisebitt et al, Nature 432 (2004) 885
Scanning transmission
X-ray microscopy
Stohr et al, Surf. Rev. Lett. 5 (1998) 1297

7. Photoemission electron microscopy (PEEM)
Schematic layout of the PEEM
(ELMITEC)
16°
X-rays
A/B ~ (A-B)/(A+B)
Circular right
Circular left
SIM beamline at the SLS
Energy range 100 – 2000 eV
Circular and linear polarization
4 µm
XMCD ~ cos(M,L)

8. Characteristics of PEEM magnetic imaging
Schematic layout of the PEEM
(ELMITEC)
Element-specific magnetic sensitivity
~50 nm spatial resolution
No magnetic interaction with the sample
Sub-ns time resolution
Variable sample temperature (100 to 800 K)
Can apply static magnetic and electric fields
Can measure linear and circular dichroism
Surface sensitive (probes 3-5 nm top layer)
Can be combined with fast laser, electric currents, and pulsed magnetic fields for dynamics studies
Also sensitive to out of plane magnetisation component, allowing 3D magnetometry
16°
X-rays
SIM beamline at the SLS
Energy range 100 – 2000 eV
Circular and linear polarization

9. XPEEM vector magnetometry
XMCD at 0o
XPEEM (SIM beamline, SLS)
Ni80Fe20 dots
E = eV (Fe L3 edge) g
2D magnetisation profile
5 mm
XMCD at 90o g
5 mm
5 mm
3D vector magnetometry in XPEEM: Guyader et al, JESRP 185 (2012) 371

10. Strain control of magnetism in Ni/PMN-PT(011)
XMCD (Ni L3)
PFM
Buzzi et al, PRL 111: (2013)

11. Wir schaffen Wissen – heute für morgen
…x-rays probe domain structure from the nano to the macro scale
…x-rays provide sensitive and element specific magnetisation maps in the static and time domains
…linearly polarised x-rays can also probe antiferromagnetic and ferroelectric domain states