The core preparation and characterization facility of the NFFA-APE laboratory is a multicomponent UHV system. This facility is designed to serve as open platform to analyse and optimize nanoscience samples, for which the sample preparation and survey represent crucial and integral part of the experiment.

at MM building at Q2 building at Elettra experimental hall at CNR-IOM cloud at Fermi-T-Rex laboratory Surface & Nano Science Lab, STM/STS PLD XPS & ambient pressure XAS ARPES & Spin ARPES MOKE & Masked deposition system XPS MBE Oxides SPRINT laboratory SEM XRD PVD data repository open data data analysis

XPS

X-ray Photoemission Spectroscopy

X-ray Photoemission Spectroscopy is available off-line with a dedicate chamber equipped with a twin-anode Mg K-alfa and Al K-alfa source and a 200mm hemispherical electrostatic analyzer for high throuput survey and core level spectra. The UHV system is part of the MBE cluster (see details). Core level photemission is also available on the APE-HE beamline (see description) covering the photon energy range 150-1500 eV with linear and circular polarized light and resolving power 3000.

Technical specifications
Analyzer type electrostatic hemispherical (mean radius 200 mm)
Field of view 100X800 microns (verticalXhorizontal)
Angular acceptance +/-8 degree in the scattering plane
Resolving power Up to 3000
Detector type 2D delay line detector with 300x300 channels
X-ray source Al, Mg K-alfa radiation
Excitation energies 1486.7 and 1253.7 eV
Sample temperature 25-300 K

MOKE

Magneto-optical Kerr effect

Magneto-optical Kerr effect measurements in situ (UHV) can be performed in the MBE cluster growth (see details) with applied magnetic field up to 0.8T on samples kept at cpntrolled temperatures in teh range 30-300 K, and with full 360-degree sample azymuthal rotation for the study of in-plane magnetic anispotropy. Vectorial MOKE at low applied fields (100Oe) is available in the Surface and Nanoscience Lab (see description).

Technical specifications
---------MOKE1- MBE Cluster ---------------------------------------------
Laser wavelength 635 nm (red) / 405 nm (blue)
Laser source WorldStarTech laser diode modules
Sample temperature range (UHV) from 400 K to 77 K (liquid N) or 5 K (liquid He)
Sample azymuthal rotation 360 degree
Maximum H Field (T) 0.58 (in UHV) / 0.8 (in air)
Minimum H-field step 0.1 mT
Pole face diameter 76 mm
Frequency filter Mechanical chopper (up to 2 kHz) / Photo Elastic Modulator (50 kHz)
Detector Thorlab PDA100A2 (red) / PDA25K-EC (blue)
Detector spectral range 320-1100 nm (red) / 150-550 nm (blue)
---------MOKE2- Surface Lab ---------------------------------------------
Laser diode laser 635nm 5mW
Polarizer and Analyzer (if necessary) Glan-Thompson prism
Detector GaAsP photodiode
Spot size approximately 100um
Sample temperature 200 K – 650 K
Max. Magnetic field transversal MOKE 600 Oe, polar MOKE 300 Oe, 3D MOKE 80 Oe

SEM

Scanning Electron Microscope

In a Scanning Electron Microscope (SEM), a beam is scanned over the sample surface in a raster pattern while a signal from secondary electrons (SE) or Back-scattered electrons (BSE) is recorded by specific electron detectors. The electron beam, which typically has an energy ranging from a few hundred eV up to 40 keV, is focused to a spot of about 0.4 nm to 5 nm in diameter. Latest generation SEMs indeed can achieve a resolution of 0.4 nm at 30 kV and 0.9 nm at 1 kV.

Technical specifications
Resolution (optimal WD) 1.0 nm @ 15kV, 1.9 nm @ 1kV
Magnification 12 -1,000,000 x
Emitter Thermal field emission type
Acceration Voltage 0.02 – 30 kV
Probe Current Configuration 1: 4pA -20nA/Configuration 2:12 pA – 100nA
Detectors High efficiency in-lens detector
Everhart-Thornley Secondary Electron Detector
Cap mounted AsB detector
Chamber 330 mm (Ø) x 270 mm (h),
2 EDS ports 35° to optional axis,
CCD-camera with IR illumination,
Additional 3rd EDS port 35° to optical axis
Specimen stage 5-Axes Motorised Eucentric Specimen Stage
X = 130 mm, Y = 130 mm, Z = 50 mm,
T = -3 - +70°
R = 360° (continuous)
6-Axes Eucentric Stage
X = 100 mm, Y = 100 mm, Z = 42 mm, Z’ = 13 mm,
T = -4 to 70°, R = 360° (continuous)
Image processing Resolution: Up to 3072 x 2304 pixel,
Noise reduction: Seven integration and averaging modes

XRD

X-ray Diffractometer

The X-ray diffraction is a technique used for the non-destructive determination of the structure of the materials, generally inorganic, and solid state. Such a technique is based on the properties of the atoms to spread out electromagnetic radiation. Assuming that the spread from each element is independent from that of the other, it is possible to formulate a theory of diffraction for three-dimensional crystal lattices.

Technical specifications
X-ray source Philips high intensity ceramic sealed tube (3kW)
Wavelength Cu Ka (1.5405 Å)
Incident beam optics interchangeable fixed slits and one Soller slit.
Diffracted beam optics fixed slit plus programmable receiving slit, graphite analyzer
Detectors sealed proportional counter
Sample stage texture cradle with sample translation
Software Philips X’PERT suite: Data Collector, Graphics & Identify, Texture
Goniometer Minimum step size 0.0001˚
Open Eulerian Cradle Chi rotation: +/- 92˚
Phi rotation: 2 x 360˚
x,y translation: 100 x 100 mm
z translation: minimum step size 1 µm

Thin film deposition and epitaxial growth systems are available at NFFA-Trieste for constructing complex materials and samples, e.g. digital heterostructures, on single-crystal substrates. Molecular Beam Epitaxy as well as Pulsed Laser-ablation Deposition offer competitive methods for in-situ single crystal thin films. E-beam sources and boat-type evaporators provide physical beams for submonolayer to few-monolayer thick deposits on surfaces at various kinetic conditions (down to cryogenic substrate temperatures) in all in-situ chambers and in-operando.

at MM building at Q2 building at Elettra experimental hall at CNR-IOM cloud at Fermi-T-Rex laboratory Surface & Nano Science Lab, STM/STS PLD XPS & ambient pressure XAS ARPES & Spin ARPES MOKE & Masked deposition system XPS MBE Oxides SPRINT laboratory SEM XRD PVD data repository open data data analysis

MBE CLUSTER GROWTH

Metal Oxide Molecular Beam Epitaxy and in-situ masked metallization/deposition

A UHV cluster offers Molecular Beam Epitaxy of oxide materials with multiple cells and ozone source and on-line RHEED. The MBE grown samples can be extracted into UHV shuttle chambers or directly transfered in situ to the surface characterization stations of the cluster that include LEED, AES, Kerr magnetometry, XPS. The shuttle UHV chamber can transfer the MBE grwn/characterized samples to the NFFA-APE beamline instruments.

Technical specifications
MBE Masked deposition
sample dimensions 5x5 mm
evaporation sources up to 5 e-bombardment evaporators
annealing temperature up to 950K
sample temperature control 35-300K
LEED / Auger spectroscopy OCI BDL800IR
transport merasurements Keithley 6487
MBE Oxide Growth
sample dimension up to 10 mm x 10 mm
deposition temperature range up to 800 K
deposition pressure in ozone/oxygen up to 10^-5 mbar
deposition pressure without process gas down to 10^-9 mbar
high temperature effusive cells (up to 1500°C) 3
conventional effusive cells 3
low temperature effusive cells 2
RHEED gun electron energy 10 kV
RHEED software analysis KSA-400
RHEED spot size 100 micron diameter

The NFFA offer includes a facility for spectroscopic investigation of solid surfaces and nanostructured matter. The NFFA laboratory is integrated with a synchrotron radiation beamline (Advanced Photoemission Experiment APE beamline), exploiting polarized synchrotron radiation in the ultraviolet and soft X-ray range from the Elettra storage ring. Photons with chosen polarization are emitted by Apple II insertion devices. The low-energy beamline (APE-LE) covers 8-120eV photon energy range dedicated to high-resolution angle-resolved photoemission (ARPES) and spin-resolved ARPES; the high-energy beamline (APE-HE) covers 150-1600 eV photon energy range used for X-ray absorption (XAS), magnetic circular/linear dichroism (XMCD, XMLD), core level photoemission (XPS).

at MM building at Q2 building at Elettra experimental hall at CNR-IOM cloud at Fermi-T-Rex laboratory Surface & Nano Science Lab, STM/STS PLD XPS & ambient pressure XAS ARPES & Spin ARPES MOKE & Masked deposition system XPS MBE Oxides SPRINT laboratory SEM XRD PVD data repository open data data analysis

ARPES and spin ARPES

Angle Resolved and Spin Resolved Photoemission Spectroscopy with variably polarized light

Angle Resolved Photoemission (ARPES) allows to measure directly the electronic band structure of crystalline solids. It is based on the photoelectric effect: the electron inside the solid absorbs energy and (negligible) momentum from the incoming photon and is ejected in vacuum where it is detected retrieving information about its initial state energy, momentum and spin. State of the art electron energy and momentum analyzers, and high energy resoution and polarization control of the exciting light are needed for resolving the fine electronic structure. Adding efficiant spin-polarization measurement to ARPES, i.e. measuring Spin Polarized-ARPES at uncompriomised energy and momentum resolution will enable addressing the study of the magnetic proporties of surfaces, interfaces and nanostructures, as well al the spin-orbit coupling effects that determine the spin texture of the surface bands in complex materials of interest for their potential in spintronics.

Technical specifications
Source Apple II Quasi-Periodic Undulator
Photon energy range (eV) 8-120
Polarization Variable (horizontal, vertical, circular ±)
Flux on sample @ 10 um slits (ph./s) >2 x 1011
Resolution (E / dE) 30000
Beam size on the sample (H X V, µm2) 150 X 50
Experimental techniques ARPES (VG-Scienta DA30 analyzer), shallow core XPS, Fermi surface mapping / tomography, Spin-resolved ARPES
Temperature range on the sample surface 15-300 K

PES, XAS/XMCD and ambient pressure XAS

Photoemission and X-ray absorption with variably polarized light

The High Energy branch (HE) of the APE beamline is devoted to the investigation of the magnetic and electronic properties of materials and nanostructures. The experimental station has the equipment for performing XAS, XMCD and XPS. Thanks to this experimental apparatus it is thus possible to gain insights on the chemical state of nanostructures and interfaces

Technical specifications
Source Apple II Undulator
Photon energy range 150-1600 eV
Polarization Variable (horizontal, vertical, circular ±)
Resolution (E/dE) up to 5000
Beam size on the sample (H x V, ) 500 x 200 microns
Entry slit reduction to 100x100 microns possible
Zone Plate optical condenser reduction to 1x3 microns possible
base pressure in end station <2x10E-10 mbar
manipulator degrees of freedom X,Y,Z + Polar and Azimuthal rotations
Sample position procision 1 micrometer
Exlectron Energy Analyzer Omicron EA 125 analyser
Sample drain current measurements Keithley 6514 picoammeter (for XAS/XMCD/XMLD)
Photon detectors 10x10 mm silicon photodiode
total ejected electron yield detector 20mm high gain channeltron
Sample temperature LT stage (while measuring) from 50 K to 300 K (He-flow cryostat)
Sample temperature HT stage (while measuring) from 300 K to 500 K
Magnetic field up to 1000 Oe in pulse mode up to 200 Oe in continuous mode
Accepted sample size 5 x 5 mm
------Ambient pressure XAS------ --------------------------
Photon energy range 150-1600 eV
Polarization Variable (horizontal, vertical, circular ±)
Resolution (E/dE) up to 5000
Silicon Nitride membrane size 500 x 500 microns
Silicon Nitride membrane thickness 100 nm
Pressure in the cell From 1x4E-10 mbar to 1 Bar
manipulator degrees of freedom X,Y
Sample position precision 1 micrometer
Sample drain current measurements Keithley 6514 picoammeter (for XAS/XMCD/XMLD)
Sample temperature (while measuring) from RT to 150 Celsius
Magnetic field up to 2000 Oe
Accepted sample size 10 x 10 mm

The European Commission encourages Open Science and FAIR data, since it is recognised that they improve and accelerate scientific research, increase the engagement of society and contribute significantly to economic growth. Therefore, all H2020 European projects that produce, collect or process research data are recommended to start dealing with the issues related, as detailed in the Guidelines on Open Access to Scientific Publications and Research Data in Horizon 2020. NFFA-Trieste supports the principle of open data access as a fundamental part of its mission.

The NFFA theory branch, by providing state-of-the-art first-principles simulations based on density functional theory, is mainly planned to support the interpretation of various experimental results obtained at other NFFA-Trieste labs. The main theory focus is on understanding microscopic mechanisms behind the observed phenomenology and investigating structure-property relationships or complex cross-coupling effects on different materials of interest. Following the comparison between theory and experiments, an “optimization” phase based on identifying guidelines and eventually performing “materials design” is available.

First-principles calculations will be performed using mainly - but not only - the Vienna Ab-initio Simulation Package (VASP, https://www.vasp.at ). A variety of exchange correlation functionals (ranging from Local Density Approximation to Generalized Gradient Approximation, from hybrid functionals to Hubbard-like DFT+U) can be used, depending on the property and systems of interest. Whenever useful, maximally-localized Wannier functions can also be constructed starting from the VASP output. Symmetry considerations will also be used as support, especially for the analysis of first-principles ferroelectric and magnetic properties. Materials in the form of bulk, interfaces, slabs, disordered alloys or different nano-structures can be considered.

 

SPIN POLARIZED VALLEYS: Upper part: E(k) band-structure plot (in the kx-ky plane) of the Valence Band Maximum in (BiIrO3)2/(BiAlO3)4 heterostructures. Colors on top (blue vs red) label spin expectation values along z direction. Band maxima coincide with the K-point (i.e. the corner in hexagonal Brillouin zone). Lower part: small green arrows denote the in-plane spin-expectation values, whereas blue/red regions show the spin-expectation value along the z-direction.

at MM building at Q2 building at Elettra experimental hall at CNR-IOM cloud at Fermi-T-Rex laboratory Surface & Nano Science Lab, STM/STS PLD XPS & ambient pressure XAS ARPES & Spin ARPES MOKE & Masked deposition system XPS MBE Oxides SPRINT laboratory SEM XRD PVD data repository open data data analysis