X-Ray Absorption Spectroscopy

MAX-PLANCK-UBC CENTRE FOR
QUANTUM MATERIALS
International Summer School on Surfaces
and Interfaces in Correlated Oxides
30th August, 2011

Giacomo Ghiringhelli
Dipartimento di Fisica
Politecnico di Milano
Italy

giacomo.ghiringhelli@fisi.polimi.it

Introducing myself...

Picture of POLIMI

Keywords:
• Synchrotron radiation
• Soft x-rays
• Resonant spectroscopy
• 3d transition metal oxides
2 Giacomo Ghiringhelli

Summary

1. Why synchrotron radiation?
• Main properties
• Absorption edges and x-ray energies
2. XAS: x-ray absorption spectroscopy
• Basic process and the choice of absorption edges
• XLD and XMCD: polarization dependent XAS
• Some examples on oxide interfaces
3. RIXS: resonant inelastic x-,ray scattering
• A second order process
• dd excitations
• Magnetic excitations


Synchrotron radiation, summary


Undulators: many photons


Undulators: polarization control

Elettroni

Campo Luce polarizzata
magnetico linearmente

Lu ce po lar izz ata
circolarmente
Elettroni

Campo
magnetico

Full control of the polarization at the source:
• Linear horizontal or vertical or any orientation (more difficult)
• Circular Right or Left handed


Beam line

High quality mirrors, gratings and crystals are needed to
make the beam monochromatic (bandas narrow as possible)
and to focalize it onto the sample

State of the art beam lines for resonant spectroscopy
Parameter Typical figures
Flux at the sample 1010 - 1013 photons/s
Beam size at sample (hoz x ver) 50 m x 5 m - 1 mm x 1 mm
Energy bandpass: UV (20 – 50 eV) 10 - 50 meV
soft x rays (300 – 1000 eV) 50 – 500 meV
hard x rays (2 - 10 keV) 50 – 500 meV


X-ray spectroscopy for 3d Transition Metal systems

E 3dTM oxides
X-ray resonant spectroscopies
Ev
• XAS: x-ray absorption
4sp spectroscopy
EF 3d • XLD and XMCD: polarization
dependent XAS
Ox 2p • RIXS: resonant inelastic x-ray
3p scattering

• Resonant reflectivity
• Resonant Elastic X-ray
2p Scattering
• Resonant Photoemission

1s


X-ray Absorption measurements
X rays

Tunable or X rays
Monochromator
“white” source
e

nA

Detection:
• transmission (only hard x-rays)
• fluorescence yield
• electron yield (including drain current)


X-ray Absorption Cross Section
log scale 2.5
OK
1 530 eV Cu L2,3
CuO
930-950 eV 2.0
Absorption coefficient (arb. u.)

Cu
0.1 M edges
1.5

0.01 Cu K
9000 eV 1.0

1E-3 Linear
0.5
scale
1E-4
0.0
10 100 1000 10000
Photon Energy (eV)

Resonances in the XAS

3d TM E Oxygen Rare Earths
4sp 6s,5d EFermi
3d 2p 4f
2s
M2,3 edges (28-77 eV) 3p

K edge 530 eV
1s
L2,3 edges (400-950 eV) 2p M4,5 edges
3d
(830-1580 eV)

K edge (4.5-9.0 keV) 1s L2,3 edges
2p
(5.5-10 keV)

Strong resonances


Core levels
C O Si Sc Fe Zn Y Mo Cd Ce Gd Lu Au Th
3dTM 4dTM RE Actinides

100000 K

Hard X-Rays
L3
10000
Binding energy (eV)

M3
M5

Soft X-Rays
1000

100

UV
2p3/2 3p
10 1s 3/2 3d5/2 4p3/2 4d5/2

0 10 20 30 40 50 60 70 80 90 100
Atomic number Z
12 - Politecnico di Milano; Source: X-ray data booklet, Lawrence Berkeley National Laboratory
GG 25/03/02 18:29:59

3p: M2,3 edge XAS
Spin-Orbit
splitting
Spin-Orbit
splitting

Source: S. Nakai, et al PRB 9, 1870 (1974)


2p: L2,3 edge XAS
Spin-Orbit
Spin-Orbit
splitting
splitting

Mn L2,3 XAS
L3
L3

La0.7Sr0.3MnO3
NiO

Ni metal
850 855 860

L2
NiO
MnO
Ni metal

850 860 870 880 640 645 650 655 660
Photon Energy (eV) photon energy (eV)
Source: G. Ghiringhelli, N.B. Brookes et al unpublished Source: C. Aruta, G. Ghiringhelli et al unpublished


Atomic model
Total E
3dTM - O
2p53dn+2L
2p53dn+1

M.S.: Multiplet
Splitting

C.I.: Configuration
3dn+1L Interaction

3dn
|g> XAS probes
orbital occupation
C.I. M.S.


L3 XAS and multiplets
Excit ation De- excitation s eout
E
CuO
h ou t

3d

h in

2p3/2
928 930 932 934
Photon Energy (eV)

Excited Ti me
Ground
Ground states
Intermediate Fin al
MnO
state stat es stat es
state
Resonant scattering without relaxation of intermediate state

3d n 2p53d n+1
CuO: 3d9  3d10 One single peak
NiO: 3d8  3d9
Many peaks
MnO: 3d5  3d6 636 638 640 642 644 646
photon energy (eV)


L3 XAS and valence

L3

L2 2.1 eV
CuO: Cu2+ is 3d9

Cu2O: Cu1+ is 3d10 CuO
Cu2O
Cu metal: 3d104s1

930 935 940
Photon Energy (eV)

Source: M. Grioni et al PRB 45, 3309 (1992) Source: M. Finazzi et al PRB 61, 4629 (2000)


X-ray absorption intensity
Fermi golden rule

Joint density
Matrix element
of states, separated
by energy h

Electric dipole perturbation
associated to a photon


Electric dipole selection rules

f ε r i
3 *
r R Ri dr
f Y ε u rYi d
*
f

Radial integral Angular integral
Mind the nodes of R! 4 0
NB what matters is Rf , ε ur Y1
3
in the presence of the
core hole!

Selection rules
(via Wigner- Eckart)
l=0

Transitions pd
l=1 Y2m '* Y1 p Y1m
m=-1,0,+1
p=-1,0,+1
l=2 m’=m-1,m,m+1


Crystal field

z Cu: x2-y2 orbital

x2-y2, z2 x2-y2
eg b1
z2
a1
x d states 10Dq 10Dq
xy
b2
yz,zx
xy, yz,zx t2g eg
y
Spherical Cubic Tetragonal
O3 Oh D4h


3d split states
t2g states

z
eg states e zx

z z
z x
y
z
x
x y
x
y
y
b2 xy x
b1 x2-y2 a1 z2 e yz y


2p states all occupied: Spherical harmonics and orbitals

anisotropy in final states
spherical distribution

3d states partly empty:
|Y1-1|2 = |Y11|2 |Y10|2
2
|Y2-2|2 = |Y22|2 |Y2-1|2 = |Y22|2 |Y20|

Y1-1=
Y11=
Y10=
22

2p to 3d transitions

2p3/2 photon 3d

• Spherical distribution • Anisotropic occupation
• No well defined spin due to crystal field
state • Possible spin polarization
• Spin “parallel” to (FM or AF)
orbital moment • Spin-orbit interaction not
always negligible
RCP = Y11
LCP = Y1-1
z-linear = Y10
x-linear = (Y1-1+Y11)/sqrt(2)

Transition of a hole from 3d to 2p

3d photon 2p3/2

Example: transition to a 3d(x2-y2) orbital

RCP = Y11

Initial state 3d hole is
100% spin down

Final state 2p hole has main spin up character

Linear polarization of x-rays: orbital occupation
Empty 3d state
Empty 3d state
E E
z
h in
h in
z

E E
x x
y y

b1 x2-y2 (Y2-2+Y22) a1 z2 Y20

High absorption (Y1-1+Y11) Weak absorption

No absorption Y10 High absorption


3d hole symmetry in cuprates

3d9 (2p3/2)33d10

h E

Result: the hole in Cu2+ has
100% x2-y2 symmetry


Linear polarization of x-rays: magnetization orientation
Atomic spin Atomic spin
orientation orientation
E E
h in
h in

E E
M
M

Different absorption Same absorption

MAGNETIC LINEAR
DICHROISM:
Works for Ferro and AntiFerro

Circular polarization of x-rays and ferromagnetic materials
XAS-MCD: x-ray absorption magnetic circular dichroism
E
z
M
Fermi level LCP
3d m
L3: 2p3/2 3d 3d
RCP
M L2: 2p1/2 3d
j=3/2
2p j=1/2
2p
3/2

sample number of matrix
free states elements
RCP
m=-1

z
transition
rates
z
m=1
LCP absorption

XAS-MCD LCP RCP
experimental geometry M L3


XMCD: sum rules
For late 3dTM sum rules allow to extract spin and orbital magnetic moments
directly from spectra without the need of theoretical simulations of spectra
8 40
Fe (L3+L2) Co Ni
7

6
L3 L2 L3 L2 L3 L2 30

Integrated Intensity (arb. units)
5 (L3+L2)
Intensity (arb. units)

4 20

3
(L3+L2)
2 10

1

0 0
(L3+L2) (L3+L2) (L3) (L3+L2)
-1 (L3) (L3)

-2 -10
700 720 740 760 780 800 820 840 860 880 900
Photon energy (eV)

XAS: some examples

Manganite thin films
• Strain and orbital occupation
• Magnetic anisotropy (FM and AF)

STO/LAO interface

Cuprates: ferromagnetism


Films of La2/3Sr1/3MnO3: strain and phase separation
Manganites:
Mn3+: 3d4
→ Mn3+/Mn4+
Mn4+: 3d3
→ CMR
LaMnO3 Mott Hubbard Insulator:
→ Phase separation Mn – Mn fluctuations
→ Orbital ordering more likely than O - Mn


Manganites XAS: strain and orbital occupation
8
100 u.c. V (E//ab)
XAS (V, H) [a.u.]

6 H (E//c) SrTiO3 substrate c/a=0.98 z2
4 x2- y2 z2
eg
2 z-in x2-y2
LSMO
0 Doct
0.3
STO t2g yz xz
V-H [a.u.]

0.0 yz xz xy
-0.3
xy
-0.6 Linear Dichroism=IXAS//ab-IXAS//c

637 644 651 658 Preferential occupation of in-plane 3dx2-y2 orbitals
Photon Energy [eV]

8
100 u.c. V (E//ab) LaAlO3 substrate c/a=1.04
XAS (V, H) [a.u.]

6 H (E//c)

4 x2- y2
x2- y2 z2
2
eg
0
0.3 LSMO z-out z2
Doct
0.0 xy
V-H [a.u.]

-0.3 t2g
yz xz xy
-0.6
LAO
yz xz

637 644 651 658
Photon Energy [eV]
Preferential occupation of the out-of-plane 3dz2–r2 orbitals


Manganites XAS: strain and dimensionality

How strain and reduced dimensionality influence
magnetic and orbital anisotropies


Manganites XAS: ferromagnetic behavior

XMCD: FM hysteresis loops


Manganites XAS: linear dichroism
LD: magnetic and orbital anisotropy


Manganites XAS: magnetic linear dichroism
MLD: ferromagnetic and antiferromagnetic anisotropy


Manganite superlattices
(SrMnO3)n/(LaMnO3)2n

LaMnO3 : Mott insulator, Mn3+, 3d4, AFM
SrMnO3 : band insulator, Mn4+, 3d3, AFM
Koida et al, PRB 66 144418 (2002)
37 Bhattacharya et al, PRL 100 257003 (2008) Giacomo Ghiringhelli

Manganite superlattices: the effect of layer thickness
n = 1, 5, 8
SMO film
LMO film

MnO2
La LaO
Sr
MnO2
O
Mn LaO
MnO2
SrO
MnO2

C. Adamo et al, App. Phys. Lett. 92, 112508 (2008)


LMO/SMO: linear dichroism

XLD at room T, no
magnetic order,
the dichroism is
given only by the
orbital occupation

C. Aruta, C. Adamo, A. Galdi, P. Orgiani, V. Bisogni, N. B. Brookes, J. C. Cezar, P. Thakur, C. A. Perroni, G. De Filippis, V.
Cataudella, D. G. Schlom, L. Maritato, and G. Ghiringhelli, Phys. Rev. B 80, 140405(R) (2009),


XLD at low T,magnetic+orbital
signal, we take out
the room T XLD to remain with
the magnetic dichroism only




What do we learn about
magnetic (AFM+FM) ordering?


LAO/STO XAS: measurements and and Ti4+ calc.

Looking for Ti3+ signal at the interface:
→ Ti4+ is 3d0
→ Ti3+ is 3d1 (like in LaTiO3)

Ti L2,3 XAS can be perfectly
simulated in single ion model
(just play with Slater integrals
and lifetime broadening)


LAO/STO XAS: linear dichroism
Linear Dichroism:
LD = Iz - Ix = Ic – Iab = IH-IV
Remember : (001) surface

M. Salluzzo, J. C. Cezar, N. B. Brookes, V. Bisogni, G. M. De Luca, C. Richter, S. Thiel, J. Mannhart,
M. Huijben, A. Brinkman, G. Rijnders, and G. Ghiringhelli, Phys. Rev. Lett. 102, 166804 (2009),


LAO/STO: anisotropy of empty 3d orbitals

→NO detectable 3d1 signal!
→In plane orbitals ar pulled
down towards EF

Vacuum Interf. Bulk LAO Interf.


Interface of STO with other materials
0.08 C. Aruta et al, unpublished LD
The trend confirms the
LDnorm (arb.u.)

0.04

role of the apical
0.00
oxygen at interface: LD
-0.04 LAO is stronger when the
LGO
NGO
overlayer has smaller
-0.08
458 460 462 464 466 468
lattice parameter
Photon energy (eV)

XMCD
When coupled to manganites
a 3d1 contribution appears
with ferromagnetism,
revealed by XMCD
F.Y. Bruno, et al. Phys. Rev. Lett. 106 147205 (2011)


Ferromagnetic signal in cuprates

La2/3Ca1/3MnO3
YBa2Cu3O7
superlattice


Cuprates: weak ferromagnetism


Cuprates XMCD: not only a question of interface

Benfatto et al. PRB 74 024416 (2006)

Djaloszinsky-Moriya interaction at the origin of weak ferromagnetism
in AF undoped compounds (La2CuO4). XMCD absent in Sr2CuO2Cl2.
We find XMCD in doped compounds too.


Cuprates XMCD: evaluating the canting angle


Second order processes

What about looking at the emitted x-rays
after a resonant absorption?

We can access local and collective excitations.
Electric dipole selection rules are not an obstacle.
Photon momentum can be used to probe dispersion.
h out
x eout
spin

sample y

z

h in
polarisation


RIXS: a resonant inelastic scattering

Etransferred=h in-h out

|i>
h in
h out

3dn+1L Charge Transfer

|f> 3dn* dd excitations
|g>

RIXS probes charge neutral local excitations


RIXS in a metal (if it had worked...)

E
J-DOS
EF

Eloss h out -h in
0

h in
h out The excited electron is bound:
the whole process creates excitations
across the Fermi level
(somehow similarly to optical
absorption).
h out depends on h in.
Actually spactra a re domiated by
fluorescence...

Resonant fluorescence, or XES

E
Projected DOS
EF
h out

h in
h out

The excited electron is “lost”:
its final energy is not important
and the emission spectrum is
independent of h in.


RIXS works well if there is a gap
Gapped systems: Charge neutral excit.:
Excitations inside Charge excit.: sharp peaks in the gap
the gap continuum
E
Eloss h out -h in
0
EF Excitation De- excitation s
E
eout

h out

h in
Strongly correlated
systems usually
give nice RIXS spectra
Time
Ground Intermediate Fin al
state states states

Low energy excitations in L2,3 edge RIXS

elastic
excited states

(C)
Intensity (arb. units)

-7 -6 -5 -4 -3 -2 -1 0 1
Relative emitted energy (eV)

Energy loss

Electronic, magnetic and vibrational excitations in RIXS

What excitations can we observe by RIXS?

Phonons
Magnetic
Electronic
dd
Optical gap CT

1meV 10meV 100meV 1eV 10eV

L edge RIXS : energy and momentum transfer

Resonant Inelastic
X-ray Scattering:
• an energy loss experiment
e E’, k’, ’
pl • made with photons of high energy
S am
• at a core absorption resonance

E, k,
Energy
Scattering plane
h = E - E’ k’

Conservation laws:
• Energy
q = k-k’
• Momentum
Momentum
• “Angular momentum” k


Photon momentum and kinematics

Photons vs Neutrons: energy and momentum

Wavevector of particles used in inelastic scattering

Thermal
neutrons
10

n s
u tro
1 Ne 1st Brillouin zone boundary
k (Ang )
-1

K edges
0.1

L edges
0.01
M edges
s
on
ot

1E-3
Ph

1m 10m 100m 1 10 100 1k 10k 100k
energy (eV)

Cuprates: the “easy” case

In cuprates Cu is divalent: Cu2+ 3d9 CuO

This makes XAS almost trivial: 1 peak only

3d9 (2p3/2)33d10
928 930 932 934
Photon Energy (eV)

RIXS can be calculated even by hand:
3d9 (2p3/2)33d10 (3d9)*

Even for magnetic excitations (spin waves),
because fast collision approximation is a very
good approximation

dd excitations in Cu2+ systems
x2-y2
x2-y2, z2 eg b1
z2
a1
d states 10Dq 10Dq
xy
b2
yz,zx
xy, yz,zx t2g eg
Spherical Cubic Tetragonal Interatomic
O3 Oh D4h exchange

x2-y2
b1
z2
a1
10Dq
xy
b2
yz,zx
eg
3d9 2p53d10 3d9

Cu L3 edge RIXS: CuO, La2CuO4, Malachite

Cu2+ in square
approximately
21
planar coordination
Cu-O distances:
Intensity (ph. s-1 eV-1)

CuO CuO 1.7 – 2-2 Ang
14 LCO 1.9 – 2.4 Ang
Malachite 1.9 – 2.6 Ang

La2CuO Different Cu2+
4 x2
7 coordination,
symmetry,
Cu2(OH) CO3 hybridization
2
0
-3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 Different dd excitations
Energy loss (eV)


Layered cuprates

By using the calculated RIXS
cross sections to fit the data the
energy of all the 3d orbitals can
be obtained from teh RIXS
spectra for any compound.

M. Moretti Sala, V. Bisogni, L. Braicovich, C. Aruta, G. Balestrino,
H. Berger, N. B. Brookes, G.M. De Luca, D. Di Castro, M. Grioni,
M. Guarise, P. G. Medaglia, F. Miletto Granozio, M. Minola, M.
Radovic, M. Salluzzo, T. Schmitt, K.-J. Zhou, G. Ghiringhelli, New
J. Phys. 13, 043026 (2011)


Ni L3 edge: NiO, NiCl2
Ni2+ (3d8) in octahedral
coordination

c
40

z
y
x

b

a
NiO
20

z

x y
NiCl
2
0 a b
-4 -3 -2 -1 0
Energy loss (eV)


Ni2+ in NiO: dependence on incident photon energy
852 853 854 855 856 857 858
Intensity (arb.u.)
NiO
Ni L3 XAS
S
P

5
852 853 854 855 856 857 NiO-5 S P
858 P
5
RIXS NiO NiCl
2
4 -4 x5 4
Energy loss (eV)

Energy loss (eV)
3 -3 3

2 -2 2

1 -1 1

0 0 0

852 853 854 855 856 857 858 0 25 50 75 100
Incident photon energy (eV) RIXS Intensity (ph. s eV -1 )
-1

G. Ghiringhelli et al , Phys Rev Lett 102, 027401 (2009)

Many excited states
relative scattered photon energy (eV)
Crystal -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0
-4.0 -3.5
field model: Sugano-Tanabe diagrams
Ni L RIXS
3
(x2-y2), (z2)
intensity (arb. u.)

F eg
10Dq
H
t2g
(xy), (yz), (zx)
1.5

10Dq (eV)
1.0
0.5 Single ion
1
G 3
P 1D 3
F
0.0 Octahedral C.F.
1
1
T2g
1 3
A1g 1g
T
3
T2g E1g
1 3
A2g 3d spin-orbit
T
3 1g
T1g Exchange
1
1.5
E
1 g
T2g 1.0
10Dq (eV)

0.5

1 3 0.0
G P 1D 3
F Single ion
4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0
relative state energy (eV)
Octahedral C.F.
G. Ghiringhelli et al, J. Phys. Cond. Mat. 17, 5397 (2005) S.G.Chiuzbaian, G. Ghiringhelli et al, Phys. Rev. Lett. 95, 197402 (2005)


Mn L3 edge: MnO, LaMnO3

15 Mn2+ and Mn3+
in octahedral
coordination

10
Mn2+: 3d5
MnO
5

LaMnO3 x10
0 Mn3+: 3d4
-10 -5 0
Energy loss (eV)


An application to thin film: Mn2+ in LaxMnO3
RIXS shows that Mn2+ is at
LaxMnO3-d/STO films site A, ie, it replaces La3+
x=La/Mn ratio
for x<1 becomes FM (self doping)

XAS reveals the presence
of Mn2+ for x<1

MnO
x=0.66
x=0.88
x=0.98
x=1.07

P. Orgiani, A. Galdi, C. Aruta, V. Cataudella, G. De Filippis, C.A. Perroni, V. Marigliano Ramaglia, R. Ciancio, N.B. Brookes, M.
Moretti Sala, G. Ghiringhelli, and L. Maritato, Phys. Rev. B 82, 205122 (2010)

STO/LAO superlattice: RIXS at Ti L3


Cuprates: not only dd excitations

600

Sr2CuO2Cl2
500

400

300

200

100

0
-8 -6 -4 -2 0
Energy loss
Giacomo Ghiringhelli (eV)

La2CuO4: 2D spin ½ Heisenberg AF insulator

Oxygen Copper

DIRECT SPACE RECIPROCAL SPACE
nuclear BZ
( , )

(0,0) ( ,0)

magnetic BZ
Elementary magnetic excitations are spin waves

Dispersing peaks: magnetic excitations SAXES
& Swiss Light Sour ce

La2CuO4

-3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5
Energy loss (eV)

LCO, comparing with INS: these are magnons!
La2CuO4

R. Coldea et al, Phys. Rev. Lett. 86, 5377 (2001).

L. Braicovich, J. van den Brink, V. Bisogni, M. Moretti Sala, L. Ament, N.B. Brookes, G.M. de Luca, M. Salluzzo, T.
Schmitt, and G. Ghiringhelli PRL 104 077002 (2010)

Another example: magnons in SCOC

Sr2CuO2Cl2

M. Guarise, B. Dalla Piazza, M. Moretti Sala, G. Ghiringhelli, L. Braicovich, H. Berger, J.N. Hancock, D. van der Marel, T.
Schmitt, V.N. Strocov, L.J.P. Ament, J. van den Brink, P.-H. Lin, P. Xu, H. M. Rønnow, and M. Grioni. Phys. Rev. Lett. 105,
157006 (2010)

What happens in doped, SC cuprates? NdBCO
Superconducting: Tc= 65K Insulating (annealed)
300
300

200
200

100 100
Intensity (a.u.)

Intensity (a.u.)
0
0

-100
-100

-200

-200

-0.6 -0.4 -0.2 0.0 0.2 -0.6 -0.4 -0.2 0.0 0.2
Energy (eV) Energy (eV)

YBCO and NdBCO family (Keimer, Le Tacon)


Theory of magnetic RIXS (1)

Single ion cross section Linear spin wave theory

Theory of magnetic RIXS (2)


CaCuO2/SrTiO3 superlattice: superconductor

D. Di Castro, M. Salvato, A. Tebano, D. Innocenti, P. G. Medaglia, M. Cirillo, and
G. Balestrino, arXiv1107.2239v1 (2011)


CaCuO2/SrTiO3 superlattice: RIXS

100 CCO bulk 400 SL n = 2
SL n=2
Norm. Intensity (arb. u.)

SL n = 3
80 SL n=3 bulk CCO
300

Energy (meV)
60
200
40
100
20

0
0
0 0.5 1.0 1.5 2.0 2.5 3.0
3.0 2.5 2.0 1.5 1.0 q//
Energy Loss (eV)

M. Minola, D. Di Castro, G. Ghiringhelli, M. Moretti Sala, N. B. Brookes, P.G.
Medaglia, A. Tebano, G. Balestrino and L. Braicovich, unpublished


Instrumentation and perspectives
With high resolution L edge RIXS
We can probe orbital and magnetic excitations
In layered cuprates we can map E(q) of magnons and
we can thus complement optical spectroscopy, EELS and INS

EXPERIMENTS
the limitations are still E resolution and intensity.

AXES at the ESRF SAXES at the SLS

From AXES (ESRF, ID08) to SAXES (SLS, ADRESS)

SAXES
& Swiss Light Sour ce
INFM
A dvanced X -Ray Emission Spectroscopy

Since 1994: AXES at beam line Since 2007: SAXES at beam line
ID08 of the ESRF ADRESS of the SLS
L = 2.2 m L = 5.0 m
Design: E/ E = 2,000 at Cu L3 (930 eV) Design: E/ E = 12,000 at Cu L3
2010: E/ E = 5,000 at Cu L3 2008: E/ E = 10,000 at Cu L3
C. Dallera et al. J. Synchrotron Radiat. 3, 231 (1996) G. Ghiringhelli, et al Rev. Sci. Instrum. 77, 113108 (2006)
G. Ghiringhelli et al., Rev. Sci. Instrum. 69, 1610 (1998) V. Strocov, T. Schmitt, L. Patthey et al, J. Synch. Rad., 17, 631 (2010).
M. Dinardo et al., Nucl, Instrum. Meth A 570, 176 (2007)

Same optical scheme:
• VLS spherical grating
• CCD detector
Different length
L

The future of RIXS instrumentation
ЄRIXS:The Єuropean RIXS facility (N.B Brookes)
E down to 30 meV at Cu L3
and 10 meV at Ti L3

10 m
Other high resolution RIXS projects:
• Centurion, at NSLS II (Brookhaven Nat Lab)
• Diamond (UK)
• MAX IV (Sweden)
• NSRRC (Taiwan)
• ...

Bibliography


X-Ray Absorption Spectroscopy

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